Apparatus and method for controlled delivery of a gas

ABSTRACT

Disclosed are apparatus for delivery of a gas, e.g., carbon dioxide and/or chlorine dioxide, and methods of its use and manufacture. The apparatus includes a sachet constructed in part with a hydrophobic material. The sachet contains one or more reactants that generate a gas in the presence of an initiating agent, e.g., water. The apparatus can also include a barrier layer and/or a rigid frame. In another embodiment, the apparatus is combined with a reservoir that can be used to deliver a gas to the reservoir and, optionally, a conduit. In another embodiment, the apparatus is incorporated into a fluid dispersion system that includes a dispersion apparatus, e.g., a humidifier.

RELATED APPLICATIONS

[0001] This application is entitled to the benefit of earlier filed U.S.Provisional Patent Application Serial. No. 60/190,028, filed Mar. 17,2000, No. 60/183,368, filed Feb. 18, 2000, No. 60/259,896, filed Jan. 4,2001, and No. 60/341,429, filed Dec. 17, 2001, under 35 U.S.C. § 119(e),and copending U.S. patent application Ser. No. 09/660,117, filed Sep.12, 2000, and Ser. No. 09/785,364, filed Feb. 16, 2001, under 35 U.S.C.§ 120, the entire disclosure of each of which are hereby incorporated byreference herein.

FIELD OF THE INVENTION

[0002] The invention relates generally to apparatus and methods fordelivery of a gas and more specifically to apparatus and methods forcontrolling the amount, rate and duration of gas delivery.

BACKGROUND OF THE INVENTION

[0003] The use of gas for retarding, controlling, killing or preventingmicrobiological contamination (e.g., bacteria, fungi, viruses, moldspores, algae and protozoa); retarding, preventing, or controllingbiochemical decomposition; controlling respiration, deodorizing and/orretarding and preventing chemotaxis to name a few, is known. Such gasesinclude, but are not limited to, chlorine dioxide, sulfur dioxide,nitrogen dioxide, nitric oxide, nitrous oxide, carbon dioxide, hydrogensulfide, hydrocyanic acid, and dichlorine monoxide. For example, the useand efficacy of chlorine dioxide is documented and discussed in variouspublications such as G. D. Simpson et al., A Focus on Chlorine Dioxide,An Ideal Biocide (visited Feb. 5, 2000)http://clo2.com/readings/waste/corrosion.html, and K. K. Krause, DDS etal., The Effectiveness of Chlorine Dioxide in the Barrier System(visited Feb. 5, 2000) http://www.dentallogic.com/dentist/effects.htm.

[0004] In particular, chlorine dioxide has been found to be useful as adisinfectant, antiseptic and sanitizer. It is used, e.g., to disinfectdrinking water and various water supplies. In addition, chlorine dioxidefinds use as a bleaching agent for flour, fats and textiles. Chlorinedioxide also has shown great utility as an antiseptic for treating metaland plastic surfaces, as well as other substrates such as countertops,meat processing and packaging equipment, and dental and medicalinstruments and devices.

[0005] One disadvantage of the prior art methods for generating chlorinedioxide gas generally is that unsatisfactory levels of by-products orreactants remain as a residue. For example, in the case of chlorinedioxide gas, the byproduct chlorite leaves residues on food handlingequipment and medical and dental surfaces. Human contact with suchresidues should be avoided or substantially minimized according to FDAand EPA regulations.

[0006] Another requirement in the food handling and related industriesis the need for raw materials or ingredients that are safe to handle inthe preparation of the disinfectant. The requirement is for theinclusion of reagents that are safe to use and, after generatingchlorine dioxide, produce side products that are non-toxic and/orbiodegradable.

[0007] Also, although it has great beneficial characteristics, chlorinedioxide can not be transported commercially as a concentrated gas forits use and instead has been generated at the site where it is used.Thus, an on-site gas generation plant typically is required to generatethe gas that is then delivered to the fluid in which it will be used.Such apparatus takes up space and represents a significant addedexpense. Moreover, even when prior art apparatus do not require aseparate gas generation component e.g., those shown in European PatentPublication No. 0 571 228 for sulfur dioxide generation, such apparatusare still undesirable because controlling the amount of gas generated,the efficiency of the generation, and the duration of the gas generationhas proven difficult, if not unsuccessful.

[0008] There exists a need for the controlled, on-site generation ofgases, such as sulfur dioxide and chlorine dioxide, which can beproduced safely, efficiently and economically, without the necessity fora separate generation plant or unwanted by-products. The presentinvention addresses these needs.

SUMMARY OF THE INVENTION

[0009] A novel approach to the delivery of gas has now been discovered.The present invention uses a unique delivery system that controls therate and efficiency of gas-producing reactions. Moreover, by usingdiscreet amounts of reactant contained within a multi-layered apparatus,the skilled practitioner can now fabricate a gas delivery apparatus thatis compact, cost-effective and safe. Furthermore, the present inventioncan be used for a variety of applications, including delivery of gas toair or water, for a variety of purposes including disinfection,deodorization, bleaching and sanitization.

[0010] In one aspect, the present invention features an apparatus fordelivery of a gas. An exemplary embodiment of this apparatus generallyincludes an envelope, a sachet disposed within the envelope, and areactant disposed within the sachet that generates a gas in the presenceof an initiating agent, wherein the envelope allows release of the gasfrom the envelope.

[0011] One currently preferred embodiment of the invention features anapparatus for delivery of a gas which includes a first reactant disposedwithin a first sachet, a second reactant disposed within a secondsachet, a third sachet disposed about the first sachet and the secondsachet, an envelope disposed about the third sachet, a frangible pouchdisposed within the envelope adjacent to the third sachet, and aninitiating agent disposed within the frangible pouch. In thisembodiment, the first reactant and the second reactant generate a gas inthe presence of the initiating agent, and the envelope allows release ofthe gas from the apparatus.

[0012] In a third exemplary embodiment, the apparatus for delivery of agas includes an envelope, a partition disposed within the envelopedefining a first volume and a second volume, a first reactant disposedin the first volume, and a second reactant disposed within the secondvolume. In this preferred embodiment, the first reactant and the secondreactant generate a gas in the presence of an initiating agent, and theenvelope allows entry of the initiating agent into the apparatus.

[0013] In another embodiment, the apparatus for delivery of a gasincludes a sachet and a reactant disposed within the sachet thatgenerates a gas in the presence of an initiating agent. In thisembodiment, the sachet allows contact of the initiating agent with thereactant and release of the gas from the apparatus.

[0014] In another aspect, the present invention features a method offorming an apparatus for delivery of a gas including the steps of (a)providing a multi-layer structure comprising a reactant layer centrallydisposed between two sachet layers, and two envelope layers disposedadjacent to the two sachet layers such that the two sachet layers arecentrally disposed between the two envelope layers, and (b) stamping themulti-layer structure such that the two envelope layers form an envelopedefined about its perimeter by the stamp, and the two sachet layers forma sachet defined about its perimeter by the stamp.

[0015] In yet another aspect, the present invention features a method ofdelivering gas including the steps of (a) providing an apparatus fordelivery of a gas comprising: an envelope, a sachet disposed within theenvelope, and a reactant disposed within the sachet that generates a gasin the presence of an initiating agent, wherein the envelope allowsrelease of the gas from the envelope; and (b) disposing the apparatus inan environment that comprises an initiating agent. The environment canbe liquid and the initiating agent can be water. Alternatively, theenvironment can be gaseous and the initiating agent can be water vapor.

[0016] In yet another embodiment, the apparatus for delivery of a gasincludes a barrier layer, a sachet layer disposed adjacent to thebarrier layer, a reactant disposed between the barrier layer and thesachet layer that generates a gas in the presence of an initiatingagent, and an envelope layer disposed adjacent to the sachet layer. Inthis embodiment, the envelope layer allows release of the gas from theapparatus.

[0017] In yet another embodiment, the apparatus for delivery of a gasincludes a barrier layer, a sachet layer disposed adjacent to thebarrier layer, and a reactant disposed between the barrier layer and thesachet layer that generates a gas in the presence of an initiatingagent. In this embodiment, the sachet layer allows entry of theinitiating agent into the apparatus.

[0018] In yet another aspect, the present invention features a method ofdelivering gas including the steps of (a) providing a multi-layerstructure comprising a reactant layer centrally disposed between asachet layer and a barrier layer, and an envelope layer disposedadjacent to the sachet layer, and (b) sealing the perimeter of thebarrier layer, sachet layer and barrier layer such that the reactant isdisposed in a volume defined by the sachet layer and the barrier layer.

[0019] In yet another aspect, the present invention features a method ofdelivering gas including the steps of (a) providing a multi-layerstructure comprising a reactant layer centrally disposed between asachet layer and a barrier layer, and (b) sealing the multi-layerstructure such that the such that the reactant is disposed in a volumedefined by the sachet layer and the barrier layer.

[0020] In yet another aspect, the present invention features a method ofdelivering gas including the steps of (a) providing an apparatus fordelivery of a gas comprising an envelope layer, a sachet layer disposedadjacent to the envelope layer, a barrier layer disposed adjacent to thesachet layer, and a reactant disposed in a volume defined by the sachetlayer and the barrier layer; and (b) disposing the apparatus in anenvironment that comprises an initiating agent.

[0021] In yet another aspect, the present invention features anapparatus for delivery of a gas including a sachet comprising a watervapor selective material, and reactant disposed within the sachet thatgenerates a gas in the presence of an initiating agent.

[0022] In yet another aspect, the present invention features anapparatus that includes a sachet including a water vapor selectivematerial, a partition disposed within the sachet defining a first volumeand a second volume, a first reactant disposed in the first volume, anda second reactant disposed within the second volume, wherein the firstreactant and the second reactant generate a gas in the presence of aninitiating agent.

[0023] In yet another aspect, the present invention features anapparatus for delivery of a gas that includes a barrier layer, a sachetlayer comprising water vapor selective material disposed adjacent to thebarrier layer, and a reactant disposed in a volume defined by thebarrier layer and the sachet layer that generates a gas in the presenceof an initiating agent.

[0024] In yet another aspect, the present invention features anapparatus for delivery of a gas that includes a sachet comprising arigid frame defining an opening and a sachet layer disposed about theopening, and a reactant disposed in the sachet, wherein the reactantgenerates a gas in the presence of an initiating agent.

[0025] In yet another aspect, the present invention features a fluiddispersion system for dispersing a gas. The system includes a fluiddispersion apparatus. and an apparatus for delivery of a gas disposedwithin the fluid dispersion apparatus. The apparatus includes a sachet,and a reactant disposed in the sachet that generates gas in the presenceof an initiating agent.

[0026] In yet another aspect, the present invention features methods fordeodorizing and/or inactivating pathogens, that includes the steps ofproviding the fluid dispersion system, and delivering the gas to one ormore odor-causing compounds, wherein the gas inactivates the one or moreodor-causing compounds.

[0027] In yet another aspect, the present invention features anapparatus for delivery of a gas to a reservoir including a sachet, areactant disposed within the sachet, and a reservoir in fluidcommunication with the sachet, wherein the reactant generates a gas inthe presence of an initiating agent.

[0028] In yet another aspect, the present invention features a method ofdelivering gas to a conduit. The method includes the step of providingan apparatus for delivery of a gas comprising a sachet, a reactantdisposed within the sachet that generates a gas in the presence of aninitiating agent, and a reservoir in fluid communication with thesachet. The method also includes the steps of coupling the apparatus toa conduit, and delivering a gas to the conduit by introducing aninitiating agent to the reactant.

[0029] In short, the invention provides the art with a heretoforeunappreciated method and apparatus for the controlled generation of agas. Moreover, in accordance with the present teachings, the inventioncan also readily be applied to the generation of a liquid.

[0030] The invention will be understood further upon consideration ofthe following drawings, description and claims.

DESCRIPTION OF THE DRAWINGS

[0031] The invention is pointed out with particularity in the appendedclaims. The drawings are not necessarily to scale, emphasis insteadgenerally being placed upon illustrating the principles of theinvention. The advantages of the invention described above, as well asfurther advantages of the invention, can be better understood byreference to the description taken in conjunction with the accompanyingdrawings, in which:

[0032]FIGS. 1A and 1B are a perspective view and a cross-sectional sideview, respectively, of an embodiment of an apparatus constructed inaccordance with the present invention;

[0033]FIGS. 2A and 2B are a perspective view and a cross-sectional sideview, respectively, of another embodiment of an apparatus constructed inaccordance with the present invention;

[0034]FIGS. 3A and 3B are a perspective view and a cross-sectional sideview, respectively, of yet another embodiment of an apparatusconstructed in accordance with the present invention;

[0035]FIGS. 4A and 4B are a perspective view and a cross-sectional sideview, respectively, of still yet another embodiment of an apparatusconstructed in accordance with the present invention;

[0036]FIGS. 5A and 5B are a perspective view and a cross-sectional sideview, respectively, of still yet another embodiment of an apparatusconstructed in accordance with the present invention

[0037]FIG. 6 is a graph depicting gas concentration versus timecomparing exemplary apparatus fabricated with and without an envelope;

[0038]FIG. 7 is a graph depicting gas concentration versus timecomparing exemplary apparatus fabricated with envelope materials havingdifferent vapor transmission rates;

[0039]FIG. 8 is a graph depicting gas concentration versus timecomparing exemplary apparatus fabricated with and without a sachet;

[0040]FIG. 9 is a graph depicting gas concentration versus timecomparing exemplary apparatus fabricated with extruded and wovensachets;

[0041]FIG. 10 is a graph depicting gas generation versus time comparingexemplary apparatus fabricated with sachets made of materials havinghydrophobic and hydrophilic surfaces;

[0042]FIG. 11 is a graph depicting gas concentration versus timecomparing exemplary apparatus fabricated with different reactant ratios;

[0043]FIGS. 12A, 12B and 12C are an exploded view, a cross-sectionalside view, and a perspective view, respectively, of one exemplaryembodiment of an apparatus constructed in accordance with the presentinvention;

[0044]FIG. 13 is a cross-sectional side view of another exemplaryembodiment of an apparatus constructed in accordance with the presentinvention;

[0045]FIG. 14 is a cross-sectional side view of yet another exemplaryembodiment of an apparatus constructed in accordance with the presentinvention;

[0046]FIG. 15 is a perspective view of still yet another exemplaryembodiment of an apparatus constructed in accordance with the presentinvention;

[0047]FIGS. 16A and 16B are a perspective view and an enlargedcross-sectional side view of a portion, respectively, of yet anotherexemplary embodiment of an apparatus constructed in accordance with thepresent invention;

[0048]FIGS. 17A and 17B are a cross-sectional side view and aperspective view, respectively, of still yet another exemplaryembodiment of an apparatus constructed in accordance with the presentinvention;

[0049]FIG. 18 is a cross-sectional side view of still yet anotherexemplary embodiment of an apparatus constructed in accordance with thepresent invention;

[0050]FIG. 19 is a cross-sectional side view of still yet anotherexemplary embodiment of an apparatus constructed in accordance with thepresent invention;

[0051]FIG. 20 is a cross-sectional side view of still yet anotherexemplary embodiment of an apparatus in accordance with the presentinvention;

[0052]FIG. 21 is a perspective view of yet another exemplary embodimentof an apparatus constructed in accordance with the present invention;

[0053]FIGS. 22A and 22B are a perspective and cross-sectional side view,respectively, of an exemplary embodiment of an apparatus including asachet constructed in part with a rigid frame;

[0054]FIGS. 23A and 23B are a perspective and cross-sectional side view,respectively, of another exemplary embodiment of an apparatus includinga sachet constructed in part with a rigid frame;

[0055]FIG. 24 is a perspective view of an exemplary embodiment of afluid dispersion system constructed in accordance with the presentinvention;

[0056]FIG. 25 is a perspective view of a housing for use with a fluiddispersion system in accordance with the present invention;

[0057]FIG. 26 is a side view of another exemplary embodiment of a fluiddispersion system constructed in accordance with the present invention;

[0058]FIG. 27 is a cross-sectional side view of another exemplaryembodiment of an apparatus for delivery of a gas to a reservoir;

[0059]FIG. 28 is a cross-sectional side view of yet another exemplaryembodiment of an apparatus for delivery of a gas to a reservoir;

[0060]FIG. 29 is a graph depicting chlorine dioxide concentration versustime comparing exemplary apparatus fabricated with different hydrophobicsachet materials; and

[0061]FIG. 30 is a graph depicting chlorine dioxide concentration versustime comparing exemplary apparatus fabricated with different hydrophobicenvelope materials.

DETAILED DESCRIPTION OF THE INVENTION

[0062] A novel approach to the delivery of gas has now been discovered.By using discrete amounts of reactant contained within a multi-layeredapparatus, the skilled practitioner can now fabricate a gas deliveryapparatus that is compact, cost-effective, and safe. The presentinvention can be used for a variety of applications, including deliveryof gas to air or water, for a variety of purposes includingdisinfection, deodorization, bleaching and sanitization.

[0063] One advantage to this approach is that gas can be generatedwithout the need for mechanical equipment, thus freeing up any spacesuch mechanical equipment would require. Another advantage is that thereactants, which can be dangerous to handle directly, are isolated fromcontact with the user by the layers, which enclose the reactant.

[0064] Another advantage is that the apparatus of the present inventiondoes not allow for the dilution of the reactant. Because the reactantremains concentrated within the sachet, less reactant is necessary todrive the reaction to completion and the reaction is more efficient thanit would be if the reactants were diluted. Furthermore, because thereaction is driven to completion, unreacted reactant is minimized oreliminated. The reactant concentration also minimizes unwantedby-products.

[0065] Yet another advantage is that the apparatus is small andtherefore can be easily and economically shipped and administered. Yetanother advantage is that the apparatus can be manipulated to allow foreither rapid or slow delivery of gas. Another advantage is that theapparatus can be designed to deliver gas to either a gas, e.g., air, ora liquid, e.g., water. Other advantages will be evident to thepractitioner having ordinary skill in the art.

[0066] In order to more clearly and concisely describe the subjectmatter of the claims, the following definitions are intended to provideguidance as to the meaning of specific terms used in the followingwritten description, examples and appended claims.

[0067] As used herein the term “sachet” means a closed receptacle forreactant. The sachet is “closed” in the sense that the reactants aresubstantially retained within the sachet and the sachet volume issubstantially sealed around its perimeter. However, the material ormaterials used to construct the sachet are chosen to allow entry of theinitiating agent and exit of the gas generated. The material ormaterials used to construct sachets are referred to herein as “sachetlayers.” Sachet layers typically are constructed from a planar material,such as, but not limited to, a polymeric sheet or film. Preferredmaterials for sachet layers are described in greater detail below.Relying upon the teaching disclosed herein, and the general knowledge inthe art, the practitioner of ordinary skill will require only routineexperimentation to identify one or more sachet layers and/or constructone or more sachets adapted for the purpose at hand.

[0068] The sachets of the present invention also can include furthermaterials, e.g., a sachet can comprise a barrier layer and sachet layersealed about the perimeters of the layers to define a closed receptaclefor reactant. Another example of a sachet is a rigid frame defining oneor more openings and one or more layers, including at least one sachetlayer, disposed about the one or more openings to define a closedreceptacle for reactant. Further examples and embodiments are describedin greater detail herein.

[0069] As used herein the term “envelope” means a closed receptaclewherein the envelope volume is sealed substantially about its perimeter,which contains at least one sachet and allows release of the gas fromthe envelope. The material or materials used to construct envelopes arereferred to herein as “envelope layers.” Envelope layers typicallycomprise a planar material such as a sheet or film, including, but notlimited to perforated films, non-perforated films and membranes.Preferred materials for envelope layers are described in greater detailbelow. Relying upon the teaching disclosed herein, and the generalknowledge in the art, the practitioner of ordinary skill will requireonly routine experimentation to identify one or more envelope layersand/or construct one or more envelopes adapted for the purpose at hand.

[0070] “Permeable layer,” as used herein, refers to a layer that permitspassage of gas generated by an apparatus of the present invention.Permeable layers typically are constructed from polymeric materials.Sachet layers and envelope layers are permeable layers.

[0071] “Impermeable layer,” as used herein, refers to a layer thatsubstantially prevents or hinders passage of initiating agent. Ascontemplated herein, the impermeable layer does not participate in thegeneration of gas in that it does not facilitate contact betweeninitiating agent and reactant. Impermeable layers can be constructedfrom various materials, including polymeric material, glass, metal,metallized polymeric material and/or coated papers. Preferred materialsfor impermeable layers are described in greater detail below. As usedherein, barrier layers are impermeable layers.

[0072] The skilled artisan will appreciate that what is considered to bean “impermeable layer” and what is considered to be a “permeable layer”is defined relative to the transmission rates of the respective layersused to construct apparatus of the present invention and the desiredshelf life of the product. Relying upon the teaching disclosed herein,and the general knowledge in the art, the practitioner of ordinary skillwill require only routine experimentation to identify and/or constructone or more impermeable layers and one or more permeable layers adaptedfor the purpose at hand.

[0073] As used herein “reactant” means a reactant or a mixture ofreactants that generate gas in the presence of an initiating agent. Forpurposes of the present invention, initiating agent includes, but is notlimited to, gaseous or liquid water. For example, for dry biocidalapplications of the present invention, such as for the reduction ofmolds when shipping fruit, moisture in the atmosphere can be used as aninitiating agent. The term “dry application” for the purposes of thisapplication means at least an application where the apparatus of thepresent invention is not immersed in water or any other liquid. The term“wet application” for the purposes of the present invention means atleast an application where the apparatus of the present invention isimmersed in water, or other liquid, which can optionally include water.For wet biocidal applications, i.e., when the apparatus of the presentinvention is immersed in water or any other aqueous medium, such as thatused for disinfecting dental or food equipment, the water in which theapparatus is immersed can be used as the initiating agent.Alternatively, the initiating agent can be included within theapparatus, e.g., contained in a frangible pouch disposed within theapparatus.

[0074] Generation of a gas, e.g., by acid activation, is well known inthe art. For example, chlorine dioxide (ClO₂) is generated from sodiumchlorite and an acid, such as citric acid, in the presence of moistureas follows.

5ClO₂ ⁻+4H⁺⇄4ClO₂+2H₂O+Cl⁻  (I)

ClO₂ ⁻→ClO₂+e⁻  (II)

[0075] Specific examples of this reaction include the following.

2NaClO₂+Na₂S₂O₈→2ClO₂+2Na₂SO₄  (III)

2NaClO₂+NaOCl+HCl→2ClO₂+2NaCl+NaOH  (IV)

[0076] Alternatively, chlorine dioxide can be produced by the reductionof a chlorate, e.g., sodium chlorate or potassium chlorate, in thepresence of an acid, e.g., oxalic acid. Generally the reaction occurs asfollows.

ClO₃ ⁻+2H⁺+e⁻→ClO₂+H₂O  (V)

[0077] For example, reduction of sodium chlorate by acidification in thepresence of oxalic acid to produce chlorine dioxide can proceed asfollows.

2 NaClO₃+H₂C₂O₄→2ClO₂+2CO₂+2H₂O  (VI)

[0078] Another example of generation of a gas by acid activation is theactivation of a sulfite, e.g., sodium bisulfite or potassium bisulfite,with an acid, e.g., fumaric acid and/or potassium bitartrate, in thepresence of moisture to form sulfur dioxide.

NaHSO₃+4H⁺⇄SO₂+2H₂O+Na⁺  (VII)

[0079] Yet another example is the acid activation of a carbonate, e.g.,calcium carbonate with an acid, e.g., citric acid, to form carbondioxide.

CaCO₃+2H⁺⇄CO₂+H₂O+Ca⁺  (VIII)

[0080] Other applications will be apparent to the skilled practitioner.For example, the generation of nitrogen dioxide by the acid activationof a nitrite, e.g., sodium nitrite or potassium nitrite. Alternativeroutes for generation of a gas, e.g., reduction of chlorates by sulfurdioxide (Mathieson Process), are well known in the art and can beutilized in accordance with the present invention.

[0081] The present invention can be used in a wide variety ofapplications. For example, chlorine dioxide can be used for thedisinfection of water, e.g., municipal water treatment: as adisinfectant for foods, beverages, fruits and vegetables; and for thecleaning and disinfection of medical, dental and food equipment.Chlorine dioxide has been shown to be an effective disinfectant atconcentrations as low as 0.2 mg/L. Chlorine dioxide is a desirablereplacement for chlorine, the traditional water treatment chemical,because it has been found to inactivate microbes at lower levels andover a wider pH range. For example, chlorine dioxide can be used toreduce or eliminate biofilms because it penetrates the cell wall ofnaturally occurring, colony-building microorganisms and disrupts theproteins necessary for reproduction. Moreover, chlorine dioxide does notproduce chlorinated by-products, e.g., trihalomethanes. Moreover, it hasbeen found to be active against pathogens that are resistant tochlorine. It can be used as a slimicide in paper or pulp machines, forwastewater treatment, and for industrial water treatment, e.g., coolingor recycle streams. It can be used for odor control or as an aerialbiocide and virucide. It can be used for the treatment of sulfides inthe oil industry, for industrial cleaning, e.g., circuit boardcleansing, and for paper or tallow bleaching. Sulfur dioxide also has avariety of uses, such as a mold and fungus inhibitor for use in shippingand storing fruits and vegetables. Based on the teachings disclosedherein the practitioner of ordinary skill will appreciate the numerousother applications for which the present invention can be used andprovides a heretofore unmet need.

[0082] The present invention relates to apparatus and methods fordelivering biocidal-effective amounts of a gas such as chlorine dioxide.The apparatus and methods of the present invention achieve delivery of adesired amount of gas, at a desired rate, over a desired time period.This is accomplished by disposing suitable reactants in a defined andconfined volume such that upon initiation, the reactants, initiatingagent, products, and by-products are held within a desired concentrationrange. The amount, rate and duration of delivery can be manipulated by,e.g., choice of sachet layers, sachet volume, reactant amount, reactantratio, envelope layers, and envelope volume. Such manipulations can beexercised by the artisan using only routine experimentation in view ofthe teachings disclosed herein together with knowledge in the art.

[0083] Generally, the present invention also relates to an apparatus fordelivery of a gas that includes reactant disposed in a volume defined byat least one permeable layer and at least one impermeable layer. The oneor more permeable layers can include a sachet layer and/or an envelopelayer, and allows release of the gas from the envelope. The one or moreimpermeable layers can include one or more barrier layer.

[0084]FIGS. 1A and 1B are a perspective view and a cross-sectional sideview, respectively, of an embodiment of an apparatus 10 constructed inaccordance with the present invention. In general overview, apparatus 10includes an envelope 20, a sachet 30 disposed within the envelope 10,and reactant 40 disposed within sachet 30 that generates a gas in thepresence of an initiating agent, e.g., water. Envelope 20 allows contactof the initiating agent with sachet 30 and release of the gas fromenvelope 20.

[0085] Apparatus 10 is particularly useful for the rapid release of agas for wet applications e.g., delivery of 5 to 50 mg chlorine dioxidegas per liter of water in 5 to 15 minutes. The function of the envelopeis to control the influx of the initiating agent, while limiting thediffusion of the reactants from the sachet to the surrounding fluid, beit gaseous or liquid. The envelope also allows the gas to diffuse to thesurrounding fluid, be it gaseous or liquid. By limiting transmission ofthe initiating agent into the apparatus, and limiting and/or preventingdiffusion of the reactants out of the apparatus, the reactant remainsconcentrated and the pH of the reactive system is localized within theapparatus to optimize the conversion of reactant to gas. Additionally,intermediates and/or by-products of the reaction, e.g., water, also cancontribute to the efficiency and/or duration of the reaction by itsaffect on the equilibrium of the reactions.

[0086] The envelope preferably is constructed of a material that isdurable and stable. Preferably, it also is capable of fusing to a likematerial upon the application of heat for construction purposes, e.g.,so that two pieces of such material can be fused about its perimeter toform the envelope. The envelope can be constructed of various materials,including polymeric material, such as perforated films, membranes andselective transmission films.

[0087] Preferably, an envelope constructed of perforated film isconstructed of envelope layers having a water vapor transmission rate(WVTR) between about 50 g/m²/24 hrs and about 1,000 g/m²/24 hrs, morepreferably, between about 200 g/m²/24 hrs and about 800 g/m²/24 hrs, andmost preferably between about 400 g/m²/24 hrs and about 700 g/m²/24 hrs.The measurement of water vapor transmission rate is routine and wellknown in the art. Also, the envelope preferably is hydrophobic.

[0088] Perforated films suitable for the construction of the envelope inaccordance with the present invention include, but are not limited to,polymeric material, e.g., Cryovac® perforated films available fromSealed Air Corporation (Duncan, S.C.). One such film is a hydrophobicpolypropylene copolymer film sold under the designation SM700 by SealedAir Corporation and has 330 holes per square inch having a diameter of0.4 mm, a 6.4% perforated area, a thickness of about 20 microns, and awater vapor transmission rate of 700 g/m²/24 hrs. Another suitable filmis a hydrophobic polypropylene copolymer film sold under the designationSM60 by Sealed Air Corporation and has 8 holes per square inch having adiameter of 0.4 mm, a 0.2% perforated area and a water vaportransmission rate of 65 g/m²/24 hrs. The artisan can readily identifysuitable equivalents of any of the foregoing by exercising routineexperimentation.

[0089] In another preferred embodiment, the envelope or envelopes can beconstructed from hydrophobic, liquid water permeable material, such aspolyethylene or polypropylene. These materials preferably are betweenabout 1 mil and about 10 mils thick with a water intrusion pressure ofabout 30 millibars or 30 millibars or less. Hydrophobic materialssuitable for use as envelope layers in accordance with the presentinvention include, but are not limited to, non-woven polyethylene suchas the TYVEK® non-woven polyethylenes from DuPont Company (Wilmington,Del.), e.g., the TYVEK® 1025D non-woven polyethylene which has anintrusion pressure of less than 30 millibars.

[0090] Envelopes can be constructed, at least in part, from ahydrophilic membrane having a pore size between about 0.01 microns andabout 50 microns. More preferably, the pore size is between about 0.05microns and 40 microns, and most preferably, the pore size is betweenabout 0.1 and about 30 microns. Preferred membranes also include, butare not limited to, the microporous ultra high density polyethylenemembrane sold under the trade designation MPLC from Millipore (Bedford,Mass.), and the microporous Nylon 6,6 membrane sold under thedesignation 045ZY by Cuno Incorporated (Meriden, Conn.).

[0091] Selective transmission films are films that are neitherperforated nor porous, but instead transfer gases through the polymerstructure of the film. Selective transmission films are multilayered ormixed polymer materials, where the layers and the polymers are chosenfor controlled transmission of gases such as carbon dioxide and oxygen.Selective transmission films are preferred in dry applications becauseit allows the gas to diffuse out of the envelope, while retaining theinitiating agent once released from a frangible pouch. Moreover, theselective transmission film increases the stability of the apparatusprior to its use because it does not easily allow ambient water todiffuse into the apparatus, which could prematurely initiate thereactants.

[0092] Generally, a film that has a high carbon dioxide transmissionrate is preferred. While not wishing to be bound to any theory, it isthought that the carbon dioxide transmission rate approximates thechlorine dioxide transmission rate because chlorine dioxide and carbondioxide are about the same size. Preferably, the selective transmissivefilm has a selective gas transmission rate of between about 500 cc/m²/24hrs and about 30,000 cc/m²/24 hrs for CO₂ and between about 1,000cc/m²/24 hrs and about 10,000 cc/m²/24 hrs for O₂. More preferably, theenvelope is constructed of a material having a selective gastransmission rate of between about 1,000 cc/m²/24 hrs and about 25,000cc/m²/24 hrs for CO₂ and between about 2,000 cc/m²/24 hrs and about10,000 cc/m²/24 hrs for O₂. Most preferably, the envelope is constructedof a material having a selective gas transmission rate of between about5,000 cc/m²/24 hrs and about 25,000 cc/m²/24 hrs for CO₂ and betweenabout 3,000 cc/m²/24 hrs and about 10,000 cc/m²/24 hrs for O₂.Measurement of selective gas transmission rate is routine and well knownin the art. One suitable selective transmission film is a multilayeredpolymer film having a carbon dioxide transmission rate of 21,000cc/m²/24 hrs and an oxygen transmission rate of 7,000 cc/m²/24 hrs soldunder the trade designation PD-961 Cryovac® selective transmission filmfrom Sealed Air Corporation (Duncan, S.C.).

[0093]FIG. 6 is a graph depicting gas concentration versus timecomparing various apparatus fabricated with and without an envelope. Thesquare-shaped data points correspond to an apparatus with an envelopeconstructed with perforated film sold under the trade designation SM60by Sealed Air Corporation (Duncan, S.C.). As described above, thisperforated film has 8 holes per square inch having a diameter of 0.4 mm,a 0.2% perforated area and a water vapor transmission rate of 65 g/m²/24hrs. The diamond-shaped data points correspond to an apparatus withoutan envelope. Both apparatus contain 50 mg sodium chlorite and 200 mgcitric acid. Both include a sachet constructed from an extrudedpolypropylene hydrophilic membrane having a 0.65 micron pore size, soldunder the trade designation JOTD obtained from Millipore (Bedford,Mass.). For both apparatus, the sachet volume was about 5.5 times thevolume of the reactants. Both apparatus were each immersed in 1 liter ofwater and the chlorine dioxide concentration measured every 5 minutesfor an hour.,

[0094]FIG. 6 demonstrates that the inclusion of an envelope increasesthe reaction efficiency, and consequently, the amount of gas deliveredfor the same amount and ratio of reactant is greatly increased. In FIG.6, the apparatus delivers about 12.5 mg of chlorine dioxide gas comparedto the approximately 4 mg delivered by the apparatus without anenvelope. Thus, the apparatus with the envelope delivered more than 3times the chlorine dioxide delivered by the apparatus without it, bothapparatus having the same amount and ratio of reactant and the samesachet layer. Moreover, FIG. 6 demonstrates the envelope increased thelength of time in which gas was generated by about 25 minutes. Ofcourse, there may be instances where having only a sachet, i.e., noenvelope, may be advantageous. For example, where the performance of theapparatus without an envelope is sufficient, having only a sachet may bepreferred because production is simplified, as the step of constructingthe envelope is eliminated, and also because material costs may bedecreased by eliminating the need to provide envelope layers toconstruct the envelope.

[0095]FIG. 7 is a graph depicting gas concentration versus timecomparing exemplary apparatus fabricated with envelope materials havingdifferent water vapor transmission rates. The triangular-shaped datapoints correspond to an apparatus without an envelope. The square-shapeddata points correspond to an apparatus with an envelope constructed fromperforated film sold under the trade designation SM700 by Sealed AirCorporation (Duncan, S.C.) having 330 holes per square inch having adiameter of 0.4 mm, a 6.4% perforated area and a water vaportransmission rate (WVTR) of 700 g/m²/24 hrs. The diamond-shaped datapoints correspond to an apparatus with an envelope constructed withperforated film sold under the designation SM60 by Sealed AirCorporation (Duncan, S.C.) having 8 holes per square inch having adiameter of 0.4 mm, a 0.2% perforated area and a water vaportransmission rate of 65 g/m²/24 hrs. All three apparatus contain thesame reactant and amount and ratio of reactant as used for the apparatusin FIG. 6. For all three apparatus, the sachet volume was about 5.5times the volume of the reactants. The reactants were enclosed sachetsconstructed from 0.65 micron pore size, hydrophobic, non-wovenpolypropylene material sold under the trade designation ANO6 byMillipore (Bedford, Mass.). These apparatus also were each immersed in 1liter of water and the chlorine dioxide concentration measured every 5minutes for an hour.

[0096]FIG. 7 demonstrates the effect of the water vapor transmissionrate of the envelope on the rate and efficiency of the reaction. In FIG.7, the apparatus having no envelope has a greater rate of reaction forabout the first 15 minutes, but is less efficient than the apparatuswith envelopes, delivering only about 12 mg of chlorine dioxide. Theapparatus having envelopes exhibit greater efficiency and a longer rateof gas generation, which is proportional to the water vapor transmissionrate (WVTR). The envelope with a water vapor transmission rate of 65g/m²/24 hrs has the greatest efficiency at about 55 minutes, generatingabout 22 mg of chlorine dioxide at a rate of about 5.5 mg of chlorinedioxide every 15 minutes. The envelope with a transmission rate of 700g/m²/24 hrs generates about 18 mg of chlorine dioxide in about 55minutes at a rate of about 4.5 mg of chlorine dioxide every 15 minutes.Thus, for applications where it is desired to increase efficiency and togenerate gas over an increased period of time, an envelope with a lowvapor transmission rate is preferred. As mentioned above, however, theremay be may be applications where having a less efficient apparatus maybe advantageous, e.g., decreased material and/or production costs.

[0097] By increasing or decreasing the water vapor transmission rate,the practitioner can control the rate and efficiency of the reaction tosuit the application. For example, it has been found that an apparatushaving a hydrophobic polypropylene envelope with a pore size of 0.1micron, a 0.65 micron pore size hydrophilic polypropylene sachet, andreactants that include 500 mg sodium chlorite and 2000 mg citric acid,will generate 3.5 mg chlorine dioxide gas per hour for at least 30hours.

[0098] It has been discovered that the use of a sachet can be used tolimit the diffusion of the initiating agent into the sachet, and limitthe diffusion of reactant and reactant by-products out of the sachet. Asa consequence, the reactants are and remain concentrated within thesachet and the pH remains localized increasing the efficiency of thereaction. Various attributes of the sachet, such as pore size, bubblepoint, and hydrophobic and/or hydrophilic nature of the sachet membrane,can be manipulated to control the affect of the sachet on the reactionas is described below.

[0099] The sachet preferably is constructed of a material that isdurable and stable. Preferably, it also is capable of fusing to a likematerial upon the application of heat or ultrasonics for constructionpurposes, e.g., so that two pieces of such material can be fused aboutits perimeter to form the sachet.

[0100] Envelopes and sachets of the present invention can be sealedabout their perimeter by any known method, such as heat sealing,ultrasonic sealing, radio frequency sealing, and sealing with adhesives.A preferred method of forming envelopes and sachets is to use an impulsesealer, which delivers a rapid and discreet thermal pulse to the layers.One impulse sealer suitable for use in accordance with the presentinvention is the 16″ TISH400 Impulse Sealer available from TEW ElectricHeating Equipment Corporation (Taiwan).

[0101] The sachet layers used to construct the sachet can be chosen tocontrol the diffusion of the reactants out of the sachet, control therate of gas release from the sachet and control the initiation of thereactants. For example, a hydrophilic sachet will increase the rate atwhich water and/or water vapor diffuses into the sachet, and the poresize and thickness of the sachet layer also will effect the passage ofwater, reactants and gas through the sachet layer.

[0102] The sachet can be constructed of various materials, includingpolymeric material or coated papers. It can be constructed from wovenmaterial, non-woven membrane, extruded membrane, or any other materialwith a controlled pore distribution having a mean pore size betweenabout 0.01 μm and about 50 μm.

[0103] A woven material is any material woven from cotton, metal,polymer threads, metal threads or the like into a cloth or mesh.Extruded membranes, which include cast membranes, are preferred, andinclude 0.65 micron pore size, 230 to 260 micron thick, hydrophilicpolyethylene membrane sold under the trade designation MPLC fromMillipore (Bedford, Mass.), 0.65 micron pore size, extruded hydrophobicpolyethylene material sold under the trade designation DOHP by Millipore(Bedford, Mass.). Also preferred is the cast membrane 3 micron poreNylon 6,6 material sold under the trade designation BIODYNE A by Pall(Port Washington, N.Y.). Non-woven membranes are membranes formed frommaterials such as cellulose or polymers. Other cast membranes include0.45 pore, hydrophilic Nylon 6,6 membranes with a polypropylene backbonesold under the designation BA05 by Cuno Incorporated (Meriden, Conn.);0.45 pore, hydrophilic polypropylene membrane available from 3M (City,State); and 0.45 pore size, 180 to 240 micron thick, hydrophilic Nylon6,6 membranes sold under the designations 045ZY and 045ZN by CunoIncorporated (Meriden, Conn.). Also suitable are hydrophobic, liquidwater permeable non-woven polyethylenes, such as the TYVEK® 1025Dpolyethylene material from DuPont Company (Wilmington, Del.).

[0104] Also suitable for use in constructing the sachet are compositelayers, including, but not limited to, starch/polymer composite layers.One currently preferred composite layer is a hydrophilic, 114 μm thick,non-woven rice starch/polyethylene composite sold under the designation60MDP-P by Mishima Paper Company, Limited (Japan). This layer is heatsealable and wets easily. Furthermore, this layer does not merely keepthe reactants apart until initiation, but functions like other preferredsachet layers of the present invention in that it controls the ratediffusion of reactants out of the sachet, controls the rate of gasrelease from the sachet, and controls the initiation of the reactant sothat the reactant remains concentrated within the sachet and thereaction is driven to completion.

[0105] Non-woven membranes can be formed, e.g., by suspending themembrane material, e.g., cellulose fibers, in a liquid over a porous weband then draining the liquid to form a membrane. Non-woven membranestypically have a relatively narrow and consistent pore size distributionas compared to woven materials. Consequently, the non-woven sachetgenerally allows less initiating agent into the sachet than the wovensachet having the same pore size because, generally the pore sizedistribution is narrower. A non-woven membrane suitable for use inaccordance with the present invention is the 0.65 micron pore size,hydrophobic, non-woven polypropylene material sold under the tradedesignation ANO6 by Millipore (Bedford, Mass.).

[0106] In a preferred embodiment the sachet is constructed from amembrane having a pore size between about 0.01 μm and about 50 μm. Morepreferably, the pore size is between about 0.05 μm and about 40 μm, andmost preferably, the pore size is between about 0.10 μm and 30 μm. Thepore size of the sachet is measured by bubble point. Bubble point is ameasurement well known in the art which approximates pore size from ameasurement of the pressure necessary to drive a bubble of gas throughthe membrane. Pore size affects the rate at which water and ions candiffuse through the sachet in both directions. A pore size preferably ischosen that allows entry of initiating agent into the sachet and, at thesame time, retains the reactants within the sachet at a highconcentration so that the reaction rate is increased and a highefficiency maintained. The artisan can readily identify suitableequivalents of any of the foregoing by exercising routineexperimentation.

[0107] Preferably, the sachet is constructed from a membrane having athickness between about 50 microns and 500 microns, more preferablybetween about 100 microns and 400 microns, and most preferably betweenabout 150 microns and 300 microns.

[0108] In certain preferred embodiments, the material used to constructthe sachet preferably has a bubble point between about 3 psi and about100 psi, more preferably between about 5 psi and about 80 psi, and mostpreferably between about 10 psi and about 70 psi. As mentionedpreviously, the measurement of bubble point is routine and well known inthe art and typically is supplied by suppliers of membranes, films,etc., however, the practitioner can readily make measurement.

[0109] Additionally, the sachet can be constructed from material that ishydrophobic and/or hydrophilic. It can also comprise a material havingone or more hydrophilic zones and one or more hydrophobic zones. Thesezones can be created, e.g., by printing a functional chemical group orpolymer onto a surface of the sachet that is hydrophilic or hydrophobicor charged to create one or more hydrophilic or hydrophobic or chargedzones. For example, a sulfonic acid group can be disposed on the surfaceof the polypropylene membrane, creating zones that are both hydrophilicand negatively charged (R—SO₂ ⁻). The membrane can then washed with adilute acid such that the ion exchange groups (R—SO₂ ⁻) bind the H⁺ions. These H⁺ ions can later be released to supply H⁺ ions to acidactivate reactant, e.g., chlorite, as a replacement or supplement toacid reactant.

[0110] When the sachet is constructed of hydrophobic material, thehydrophobic material preferably has a flow time between about 10 sec/500ml and about 3,500 sec/500 ml for 100% IPA at 14.2 psi. More preferably,the material has a flow time between about 60 sec/500 ml and about 2,500sec/500 ml for 100% IPA at 14.2 psi, and most preferably, the materialhas a flow time between about 120 sec/500 ml and about 1,500 sec/500 mlfor 100% IPA at 14.2 psi.

[0111] When the sachet is constructed of hydrophilic material asdescribed above the hydrophilic material preferably has a flow timebetween about 5 sec/500 ml and about 800 sec/500 ml for 100% IPA at 14.2psi. More preferably, the material has a flow time between about 20sec/500 ml and about 400 sec/500 ml for 100% IPA at 14.2 psi, and mostpreferably, the material has a flow time between about 50 sec/500 ml andabout 300 sec/500 ml for 100% IPA at 14.2 psi. Measurement of flow timeis routine and well known in the art.

[0112] Yet another alternative embodiment uses a material to constructthe sachet that has a first surface that is hydrophilic and a secondsurface that is hydrophobic. For example, a sachet can be constructedfrom such a material such that the hydrophilic surface is on the outsideof the sachet and the hydrophobic surface is on the inside of thesachet. The exterior, hydrophilic surface aids the initiation of thereaction since water will readily wet a hydrophilic surface and enterthe sachet. However, once inside the sachet, the hydrophobic, interiorsurface limits water passage out of the sachet. This keeps the reactantsconcentrated within the sachet while allowing the gas to escape thusexploiting the advantages of the discoveries disclosed herein. One suchmaterial suitable for use in the present invention is a non-wovenmembrane 0.65 micron pore size diameter formed from a hydrophobicmaterial, such as polypropylene, that has been chemically functionalizedwith amines and carboxyl groups to produce a charge, hydrophilicsurface.

[0113] The ratio of sachet volume to reactant volume also can bemanipulated to control the concentration of the reactants,intermediates, by-products, etc. within the sachet. As discussedpreviously, increasing the concentration of reactants generallyincreases reaction efficiency. Preferably the sachet volume is less thanabout 20 times the volume of reactant, more preferably less than about10 times the volume of the reactant. Most preferably, it is less than 6times the volume of the reactants. Smaller volumes are preferred incertain applications because when the ratio of sachet volume to reactantvolume is small, water produced in the reaction increases the pressureinside the sachet reducing the rate at which water can diffuse into thesachet, the water to reactant ratio remains constant and thus the rateof reaction remains constant. Preferably the volume of the envelope isfrom about 2 to about 6 times the volume of the sachet.

[0114]FIG. 8 is a graph depicting gas concentration versus timecomparing exemplary apparatus fabricated with and without a sachet.Specifically, FIG. 8 depicts gas concentration versus time comparingdelivery of chlorine dioxide gas from reactant within a sachet versusreactant added directly to water, i.e., with neither sachet norenvelope. The triangular-shaped data points indicate the rate ofdelivery of chlorine dioxide over time in 1 liter of water from a sachetmaterial constructed from a 0.65 micron pore size, hydrophilicpolypropylene membrane sold under the trade designation MPLC byMillipore (Bedford, Conn.). The sachet contained 200 mg citric acid and50 mg of sodium chlorite. The sachet volume was about 5.5 times thevolume of the reactants. The sachet was enclosed in an envelopeconstructed from perforated film sold under the trade designation SM700by Sealed Air Corporation having 330 holes per square inch having adiameter of 0.4 mm, a 6.4% perforated area and a water vaportransmission rate of 700 g/m²/24 hrs. The diamond-shaped data pointsindicate the rate of delivery of chlorine dioxide over time when thesame reactants in the same amounts were added to 1 liter of waterdirectly, i.e., with neither sachet nor envelope. The apparatus with thesachet delivered more than 10 times the chlorine dioxide than when thereactants were added directly to the water. As can be seen from FIG. 8,the sachet increases the efficiency of the reaction.

[0115]FIG. 9 is a graph depicting gas concentration versus timecomparing an exemplary apparatus fabricated with extruded and non-wovensachets. The diamond-shaped data points indicate delivery of chorinedioxide over time for the apparatus with a sachet constructed from 0.65micron pore size, hydrophobic, non-woven polypropylene material soldunder the trade designation ANO6 by Millipore (Bedford, Mass.). Thesquare-shaped data points indicate delivery of chorine dioxide over timefor the apparatus with a sachet constructed from 0.65 micron pore size,extruded hydrophobic polypropylene material sold under the tradedesignation DOHP by Millipore (Bedford, Mass.). Both sachets contained200 mg citric acid and 50 mg of sodium chlorite and the sachet volumewas about 5.5 times the volume of the reactants. Neither apparatusincluded an envelope. The apparatus were each immersed in 1 liter ofwater and the chlorine dioxide gas concentration measured every fiveminutes for an hour.

[0116] As shown in FIG. 9, both apparatus deliver chlorine dioxide atapproximately the same rate for about the first 20 minutes. However, asthe reactants become increasingly dilute in the extruded sachet relativeto the non-woven sachet, the rate of the chlorine dioxide releasediminishes. The efficiency of the reaction in the apparatus with thenon-woven sachet is greater than that with the extruded sachet. Theapparatus with the non-woven sachet also continue to generate chlorinedioxide gas at a rate of about 2 mg every 5 minutes for about 15 minuteslonger than the apparatus with the extruded sachet. As mentioned above,non-woven sachets generally have a relatively narrow pore sizedistribution, and without wishing to be bound to any theory, it isthought that this accounts for the greater efficiency and longer periodof gas generation. Thus, FIG. 9 provides a non-limiting illustration ofhow sachet material choice, and thus reactant concentration, can beexploited to sustain the rate of gas release and increase theefficiency.

[0117]FIG. 10 is a graph depicting gas generation versus time comparingexemplary apparatus fabricated with sachets made of materials havinghydrophobic and hydrophilic surfaces. The triangular-shaped data pointscorrespond to an apparatus with a sachet constructed from 0.65 micronpore size, hydrophilic polypropylene sachet sold under the tradedesignation MPLC from Millipore (Bedford, Mass.). The diamond-shapeddata points correspond to an apparatus with a sachet constructed from0.65 micron pore size, extruded hydrophobic polypropylene material soldunder the trade designation DOHP by Millipore (Bedford, Mass.). Thesquare-shaped data points correspond to adding the reactant directly tothe water. The reactant was 200 mg citric acid and 50 mg of sodiumchlorite and the sachet volume was about 5.5 times the volume of thereactants. Neither sachet was enclosed in an envelope. The apparatus andthe reactant were each immersed in 1 liter of water and the chlorinedioxide gas concentration was measured every 5 minutes for an hour.

[0118]FIG. 10 demonstrates that apparatus having a hydrophobic sachetresults in a more efficient reaction that generates gas over a longerperiod of time than a hydrophilic sachet. In FIG. 10, the apparatus withthe hydrophobic sachet generated chlorine dioxide for about 30 minutesat about 2 mg every 5 minutes. In contrast, the apparatus with thehydrophilic sachet generated chlorine dioxide only for about 10 minutesat about 2 mg every 5 minutes. As disclosed above in connection withFIG. 6, adding an envelope to either sachet will have the effect ofincreasing the efficiency of the reaction as well as increasing thelength of time in which gas is generated.

[0119] The reactant preferably comprises an aqueous soluble acid and areactant that upon acid activation generates a gas. For example, for thegeneration of chlorine dioxide, preferably the reactant comprises anaqueous soluble acid and an aqueous soluble chlorite. For the generationof sulfur dioxide, preferably the reactant comprises an aqueous solubleacid and an aqueous soluble sulfite. Other examples of gas generatingreactions are disclosed above.

[0120] Any acid can be used as a reactant. However, weak acids arepreferred, as they typically are safer to handle, produce lessundesirable by-products, and are less reactive. Also, multifunctionalacids are preferred. Multifunctional acids are acids that have more thanone reactive site. For example, the trifunctional acid, citric acid, ispreferred. Preferably, the aqueous soluble acid is selected from thegroup consisting of phosphoric acid, fumaric acid, glycolic acid, aceticacid, ascorbic acid, oxalic acid, maleic acid, lactic acid, tartaricacid, citric acid and mixtures thereof. More preferably, the aqueoussoluble acid is selected from the group consisting of ascorbic acid,phosphoric acid, oxalic acid, maleic acid, lactic acid, tartaric acid,citric acid and mixtures thereof. Most preferably, the aqueous solubleacid is ascorbic acid, oxalic acid, citric acid and mixtures thereof.

[0121] For applications involving the generation of chlorine dioxide,preferably the aqueous soluble chlorite is selected from a groupconsisting of sodium chlorite and potassium chlorite and mixturesthereof. Preferably sodium chlorite is used.

[0122] Preferably, the weight ratio of the aqueous soluble chlorite tothe aqueous soluble acid is between about 1:2 to about 1:6, preferablyfrom about 1:2.5 to about 1:5, most preferably from about 1:3 to about1:4.5. Preferably, a pH between about 1.5 to 5.5, more preferably a pHof about 2, is maintained by using an excess of acid. Because thereactants are concentrated within the sachet, less acid is needed todrive the reaction to completion and the pH remains low because the acidis concentrated. Furthermore, chlorite is consumed by acid and thereforethe presence of chlorite is minimized.

[0123]FIG. 11 is a graph depicting gas concentration versus timecomparing apparatus fabricated with two different reactant ratios. Thesquare-shaped data points correspond to an apparatus with a 1:4 ratio ofcitric acid to sodium chlorite (50 mg sodium chlorite and 200 mg ofcitric acid). The diamond-shaped data points correspond to an apparatuswith a 1:1 ratio of citric acid to sodium chlorite (50 mg sodiumchlorite and 50 mg citric acid). Both apparatus included a sachetconstructed from 0.65 micron pore size, hydrophilic, polypropylenesachet sold under the trade designation MPLC from Millipore (Bedford,Mass.). The sachet volume was about 5.5 times the volume of thereactants. Both sachets were enclosed in an envelope constructed fromperforated film sold under the trade designation SM700 by Sealed AirCorporation having 330 holes per square inch having a diameter of 0.4mm, a 6.4% perforated area and a water vapor transmission rate of 700g/m²/24 hrs. These apparatus were immersed in 1 liter of water and thechlorine dioxide gas concentration measured every 5 minutes for an hour.

[0124]FIG. 11 demonstrates that increasing the amount of citric acidrelative to the amount of sodium chlorite increases the efficiency ofthe reaction, in part because the excess of acid drives the reaction tocompletion. The relationship of efficiency to reactant ratio is fairlypredictable when the ratio of sodium chlorite to citric acid is betweenabout 1:1 and about 1:6. Above about 1:6, there is little change in theefficiency of the reaction.

[0125] Ambient temperature also can affect the efficiency of thereaction. Generally, the hotter the temperature of the ambient fluid,e.g., water or air, the more efficient the generation of gas. Generally,however between the ranges of 10° C. and 40° C., the efficiency improvesas the temperature increases. The data used to generate FIGS. 6 through11 and the Examples are from apparatus tested at from about 23° C. toabout 25° C. The sachet also can include various other ingredients thatwill be obvious to one skilled in the art, such as drying agents,stabilizers, and buffers to control the pH.

[0126] It also should be understood that the apparatus and methods ofthe present invention also are readily applicable to the delivery ofmore than one gas at one time. For example, the reactant can includeboth a chlorite and at sulfite for the delivery of both chlorine dioxideand sulfur dioxide.

[0127]FIGS. 2A and 2B are a perspective view and a cross-sectional sideview, respectively, of another embodiment of an apparatus 110constructed in accordance with the present invention. In generaloverview, apparatus 110 includes envelope 120 and two sachets 132, 134disposed within the envelope 120. Sachets 132, 134 contain reactant 142,144, respectively.

[0128] Apparatus 110 is particularly useful for the delivery of gas inwet applications. In such applications, reactant 142, 144 can be, e.g.,sodium chlorite and acid respectively, the sachet can be constructedfrom a material with a pore size large enough to allow diffusion ofsodium chlorite and acid reactant out of the sachets, and the envelopecan be chosen that does not allow the reactants to diffuse from theapparatus and regulates the release of gas from the apparatus so thatthe reaction remains efficient.

[0129] The envelope and sachet can be constructed from any of thematerial discussed in references to FIGS. 1A and 1B. Preferably, theenvelope is a hydrophobic perforated film, such as the polypropylenecopolymer film sold under the designation SM700 by Sealed AirCorporation (Duncan, S.C.) having 330 holes per square inch having adiameter of 0.4 mm, a 6.4% perforated area and a water vaportransmission rate of 700 g/m²/24 hr. The envelope can also beconstructed from 0.65 micron pore hydrophobic polypropylene membrane,such as that sold under the trade designation DOHP by Millipore(Bedford, Mass.).

[0130] For wet applications, most preferably the envelope is constructedfrom a cast membrane. Suitable cast membranes can be chosen to regulatethe entry of initiating agent into the apparatus based on the thicknessof the layer, the pore size and the hydrophobic and/or hydrophilicnature of the membrane. The thickness of the membrane is preferablybetween about 50 microns and about 500 microns, more preferably betweenabout 100 microns and about 400 microns, and most preferably betweenabout 150 microns to about 350 microns. The pore size preferably isbetween about 0.05 microns to about 5 microns, more preferably betweenabout 0.2 microns and about 1.2 microns, most preferably between about0.48 microns and 0.85 microns. A non-woven membrane suitable for use inaccordance with the present invention is the 0.60 pore size,hydrophobic, polypropylene membrane having a thickness between about 250microns and about 300 microns sold under the designation 060P1 by CunoIncorporated (Meriden, Conn.).

[0131] Sachets 132, 134 can be constructed from hydrophobic membraneand/or hydrophilic membrane. Preferred materials for sachets 132, 134are described in connection with the embodiment of FIGS. 1A and 1B.Preferably, the sachets 132, 134 are constructed from a hydrophilicmaterial, e.g., 0.65 micron pore size hydrophilic polypropylenemembrane, such as that sold under the designation MPLC by Millipore(Bedford, Mass.), or extruded polypropylene hydrophilic membrane havinga 0.65 micron pore size, sold under the trade designation JOTD obtainedfrom Millipore (Bedford, Mass.), or a 114 μm thick, non-woven ricestarch polyethylene composite sold under the designation 60MDP-P byMishima Paper Company, Limited (Japan). Also preferred are the 1.2micron and 2 micron pore, hydrophilic Nylon 6,6 membranes sold under thedesignations 120ZY and 200ZY, respectively, by Cuno Incorporated(Meriden, Conn.), and the 1.2 and 2.0 micron pore size, hydrophilicpolypropylene membranes sold under the designation MPLC by Millipore(Bedford, Mass.).

[0132] For wet applications, the pore size of the sachet membranepreferably is between about 0.01 microns to about 30 microns, morepreferably between about 0.05 microns and about 20 microns, even morepreferably between about 0.1 microns and about 10 microns, mostpreferably between about 1.2 microns and 5 microns. A pore size ofbetween about 1.2 microns and 5 microns is preferred in certainembodiments. Without wishing to be confined to any particular theory, itis believed that sachet layers with pore sized in the most preferredrange allow rapid passage of the initiating agent into the reactant anddiffusion of the reactant into the envelope. The envelope would then bechosen with a pore size that does not allow significant diffusion of thereactant out of the apparatus. The thickness of the sachet membranepreferably is between about 50 microns and about 500 microns, morepreferably between about 100 microns and about 400 microns, and mostpreferably between about 150 microns to about 350 microns.

[0133] Reactant 142, 144 preferably includes an aqueous soluble acid andan aqueous chlorite that upon acid activation generates a gas.Preferably, these components are not mixed, but instead are separatelycontained in sachets 132, 134. It is preferred to separately contain thechlorite and the acid because this minimizes the likelihood of prematureinitiation, e.g., during storage and shipment. Reactant 142, 144 can beliquid or solid, but is preferably solid.

[0134] Preferably the citric acid has a particle size of between about15 microns and about 55 microns and is desiccated until about 6-8% ofthe initial weight is removed as excess moisture prior to incorporationinto the apparatus of the present invention. Preferably the sodiumchlorite has a particle size of between about 15 microns and about 55microns and is desiccated to remove excess moisture prior toincorporation into the apparatus of the present invention.

[0135] In a preferred embodiment, the envelope 120 is hydrophobic andthe sachets 132, 134 are hydrophilic. This preferred embodiment isparticularly suitable for the delivery of gas in wet applications andhas a slower rate of gas delivery than apparatus 10 of FIGS. 1A and 1B.For example, this embodiment can be used to deliver gas at low ratesover long periods of time, e.g., 20 mg of gas per hour over a 24 hourperiod. This embodiment also is preferred for applications where a highefficiency and concentration of gas is desired and it is possible toallow the apparatus a period of time to complete delivery, e.g., 4 to 8hours. This application also is preferred when working with relativelylarge amount of reactants that otherwise might begin reacting duringconstruction and storage of the apparatus, e.g., when constructing anapparatus having more than about 1 gram of sodium chlorite and 4 gramsof citric acid. This embodiment is particularly useful for controllingand preventing biofilm contamination and as a disinfectant, antisepticand sanitizer in applications where water is stored or conducted throughconduits, e.g., in swimming pools, water tanks, humidifiers, boat lines,beverage lines and the like.

[0136] Optionally, this embodiment could contain a second envelope (notshown) enclosing the first envelope 120. This second envelope might beuseful, for example, in further regulating the introduction of theinitiating agent through the envelope walls.

[0137] Optionally, this embodiment could contain a third sachet asdepicted in FIG. 19, which is a cross sectional side view of apparatus1210 constructed in accordance with the present invention. Apparatus1210 generally includes envelope 1220, and sachets 1232, 1234 and 1236,disposed within envelope 1220. Sachets 1232, 1234 and 1236 containreactant 1242, 1244, and 1246, respectively. This embodiment isparticularly useful, for example, when it is desired to separate acidand chlorite into separate sachets and the volume of one issignificantly greater than the other, e.g., the volume of acid isgreater than the volume of chlorite. In this instance, one can separatethe acid 1242 and 1246, into two sachets 1232, 1236 that are disposed oneach side of the chlorite 1244 disposed within sachet 1234. Thisembodiment is preferred when using larger amounts of reactant, e.g., onecould construct an apparatus similar to that depicted in FIG. 19, with 2grams of sodium chlorite in one sachet, disposed between two sachetswith 4-5 grams of citric acid in each. All other variables being equal,this embodiment is more efficient than embodiments having only twosachets when working with larger amounts of reactant. This embodimentalso is easier to manufacture.

[0138] In a currently preferred embodiment, the reactant includes citricacid disposed in sachets 1232, 1236 and sodium chlorite is disposed insachet 1234. The sachets 1232, 1234, 1236 are constructed from 114 μmthick, non-woven rice starch polyethylene composite sold under thedesignation 60MDP-P by Mishima Paper Company, Limited (Japan), and theenvelopes are constructed from 0.60 pore size, hydrophobic polypropylenemembrane having a thickness between about 250 microns and about 300microns sold under the designation 060P1 by Cuno Incorporated (Meriden,Conn.).

[0139] This embodiment is particularly useful for controlling andpreventing contamination and as a disinfectant, antiseptic and sanitizerin applications where water is stored or conducted through conduits,e.g., in swimming pools, water tanks, humidifiers, boat lines, beveragelines and the like.

[0140]FIGS. 3A and 3B are a perspective view and a cross-sectional sideview, respectively, of an apparatus 210 constructed in accordance withthe present invention. Apparatus 210 includes first sachet 232, firstreactant 242 disposed within first sachet 232, second sachet 234, secondreactant 244 disposed within second sachet 234, third sachet 250disposed about first sachet 232 and second sachet 234, and envelope 220disposed about third sachet 250. Disposed within the envelope 220adjacent to the third sachet 250 is frangible pouch 260, and initiatingagent 264 disposed within frangible pouch 260.

[0141] Apparatus 210 is particularly useful for the delivery of gas in adry application because initiating agent 264 is contained within theapparatus 210. In this embodiment, first reactant 242 and secondreactant 244 generate a gas in the presence of initiating agent 264. Forthis to occur, frangible pouch 260 is ruptured, e.g., by exertingpressure on frangible pouch 260 so that initiating agent 264 isdelivered into first envelope 220. Third sachet 250 allows contact ofinitiating agent 264 with first sachet 232 and second sachet 242.

[0142] First sachet 232, second sachet 234, first reactant 242 andsecond reactant 244 are described above in reference to the embodimentsshown in FIGS. 1A, 1B, 2A and 2B. In a currently preferred embodiment,first sachet 232 and second sachet 234 are constructed from ahydrophilic material having a pore size between about 3 microns and 5microns. A suitable material is a 3 micron pore Nylon 6,6 material soldunder the trade designation BIODYNE A by Pall (Port Washington, N.Y.).

[0143] Third sachet 250 preferably is constructed using the materialsdescribed above in reference to the sachet material for the embodimentsdescribed for FIGS. 2A and 2B. The materials described above inreference to the embodiment described for FIGS. 1A and 1B can also beused. A suitable sachet layers is 0.65 micron pore hydrophobicpolypropylene membrane, such as that sold under the trade designationDOHP by Millipore (Bedford, Mass.). The third sachet limits thediffusion of reactant out of the third sachet and thus, it keeps thereactant concentrated within the third sachet and the pH localized.Preferably, the third sachet volume is less than 4 times that of thefirst reactant and the second reactant combined, and most preferablyless than 2 times that of the first reactant and the second reactantcombined.

[0144] Preferably, envelope 220 is constructed from a selectivetransmission film. Selective transmission films are described above inconnection with FIGS. 1A and 1B. As discussed above, selectivetransmission films are preferred in dry applications because it allowsthe gas to diffuse out of the envelope, while retaining the initiatingagent once released from the frangible pouch. Moreover, the selectivetransmission film increases the stability of the apparatus prior to itsuse because it does not easily allow ambient water to diffuse into theapparatus, which could prematurely initiate the reactants. Furthermore,keeping the reactant, e.g., sodium chlorite and acid, separated into twosachets also can increase the stability of the apparatus because itretards initiation should initiating agent diffuse into the apparatusprior to rupturing the frangible pouch.

[0145] One suitable selective transmission film is a multilayeredpolymer film having a carbon dioxide transmission rate of 21,000cc/m²/24 hrs and an oxygen transmission rate of 7,000 cc/m²/24 hrs soldunder the trade designation PD-961 Cryovac® selective transmission filmfrom Sealed Air Corporation (Duncan, S.C.).

[0146] Frangible pouch 260 can be constructed of any material thatruptures when pressure is applied to the envelope thus releasing theinitiating agent inside it. Preferably, the frangible pouch isconstructed from a multi-layer plastic, e.g., polyolefin, envelopehaving a weak layer positioned near the sealing surface that will failunder pressure. Initiating agent 264 can be any agent that initiates agas-generating reaction, e.g., water. Preferably the initiating agent iswater or an aqueous solution, but is not limited thereto.

[0147] The skilled practitioner will appreciate that the first reactant242 and the second reactant 244 can be combined and disposed in a singlesachet, i.e., first sachet 232 and second sachet 234 can be combinedinto a single sachet (not shown). Moreover, the initiating agent 264disposed in frangible pouch 260 can be disposed within the volumedefined by the third sachet 250 (also not shown).

[0148]FIGS. 4A and 4B are a perspective view and a cross-sectional sideview, respectively, of still yet another embodiment of an apparatus 310constructed in accordance with the present invention. In generaloverview, apparatus 310 includes sachet 370 and partition 380 disposedwithin sachet 370 defining first volume 382 and second volume 384 withinsachet 370. Also shown is first reactant 342 disposed within firstvolume 382 and second reactant 344 disposed within second volume 384. Inthis embodiment, first reactant 342 and second reactant 344 generate agas in the presence of an initiating agent, and sachet 370 allows entryof an initiating agent into apparatus 310.

[0149] Preferably, sachet 370 is constructed using a hydrophobicmembrane to retard entry of the initiating agent into the apparatus.Preferably, partition 380 is constructed using hydrophilic membrane sothat the initiating agent, once within the apparatus, will migrate topartition 380. These hydrophobic and hydrophilic membranes are describedabove for the embodiments depicted in FIGS. 1A, 1B, 2A, and 2B.Similarly first reactant 342 and second reactant 344 are described abovefor the embodiments depicted in FIGS. 1A, 1B, 2A, and 2B. If, forexample, first reactant 342 consists of sodium chlorite and secondreactant 344 consists of citric acid, reaction begins when an initiatingagent reaches partition 380. In a preferred embodiment, sachet 370 isconstructed from 0.65 micron pore hydrophobic polypropylene membrane,such as that sold under the trade designation DOHP by Millipore(Bedford, Mass.), and partition 380 is constructed from 0.65 micron porehydrophilic polypropylene membrane, such as that sold under thedesignation MPLC by Millipore (Bedford, Mass.).

[0150] Optionally, the apparatus depicted in FIGS. 4A and 4B may furthercomprise an envelope (not shown) enclosing the sachet. This envelope canbe constructed from any of the envelope materials described above forthe embodiments depicted in FIGS. 1A, 1B, 2A and 2B. Preferably, theenvelope is a hydrophobic perforated film, such as the polypropylenecopolymer film sold under the designation SM700 by Sealed AirCorporation (Duncan, S.C.) having 330 holes per square inch having adiameter of 0.4 mm, a 6.4% perforated area and a water vaportransmission rate of 700 g/m²/24 hr. In a currently preferredembodiment, the envelope is constructed from a selective transmissionfilm, such as the PD-961 Cryovac® selective transmission film fromSealed Air Corporation (Duncan, S.C.) disclosed above in connection withFIGS. 3A and 3B. Additionally, the apparatus can further comprise afrangible pouch, and initiating agent disposed within frangible pouch,disposed within the envelope.

[0151]FIGS. 5A and 5B are a perspective view and a cross-sectional sideview, respectively, of still yet another embodiment of an apparatus 410constructed in accordance with the present invention. In generaloverview, apparatus 410 includes sachet 430 and reactant 440 disposedwithin sachet 430 that generates a gas in the presence of an initiatingagent. Sachet 430 allows contact of the initiating agent with thereactant and release of the gas from the apparatus.

[0152] There may be instances where having only a sachet, i.e., noenvelope, may be preferred over embodiments that further includeenvelopes. For example, where the performance of the apparatus withoutan envelope is sufficient, this embodiment is preferred, becauseproduction is simplified as the step of constructing the envelope iseliminated, and also because material costs may be decreased byeliminating the need to provide envelope layers to construct theenvelope.

[0153] Sachet materials can be constructed from the materials describedabove for the embodiments depicted in FIGS. 1A, 1B, 2A, and 2B.Preferably, the sachet is constructed using hydrophobic membrane so thatthe sachet limits the amount of water entering the sachet. Similarly,reactant 440 is described above for the embodiments depicted in FIGS.1A, 1B, 2A, and 2B.

[0154]FIGS. 8, 9, and 10 depict concentration versus time for variousapparatus that include a sachet but do not include envelopes. Acurrently preferred embodiment is an apparatus where the sachet isconstructed from a 0.65 micron pore size, hydrophobic polypropylenemembrane sold under the trade designation DOHP by Millipore (Bedford,Mass.). The diamond-shaped data points in FIGS. 9 and 10 depict theperformance of an apparatus with a sachet and without an envelopeconstructed from this material.

[0155] In view of the collective teachings and guidance set forthherein, the practitioner can design, fabricate, test and use any numberof embodiments of the present invention. All that is required is anordinary level of skill in the art and some routine experimentation. Forexample, for a disinfection application, a practitioner initially shoulddetermine the volume to be disinfected using a gas-generating apparatusof the instant invention. Next, appreciating that the current standardfor cold sterilization/disinfection is 5 mg/L chlorine dioxide, thepractitioner should determine the quantity of chlorine dioxide that willbe required to disinfect the desired volume.

[0156] From the volume of chlorine dioxide gas required, the amount andratio of reactant necessary to generate this amount of chlorine dioxidecan be calculated. Of course, if a practitioner wishes to increase ordecrease the disinfecting concentration, then one can adjust thereactant quantities placed in a sachet. Representative data generatedwith varying ratios of reactants are depicted in FIG. 11, for example.Variations in amounts generally are proportional, e.g., doubling theamount of sodium chlorite will double the amount of chlorine dioxide gasgenerated, if all other elements of the apparatus remain the same. Ofcourse, the amount of gas generated can also be increased by envelopechoice as described in connection with FIGS. 6 and 7.

[0157] Also, the practitioner should determine the time course ofrelease of the disinfecting gas and choose sachet layers and envelopelayers accordingly. For example, if a rapid release is desired, thenreactants can be contained within a sachet fabricated from hydrophilicmaterial; if a less rapid release is desired, then reactants can becontained in a hydrophobic material. Representative data generated withhydrophobic and hydrophilic sachet material are depicted in FIG. 10.Representative data generated with reactants housed in variousembodiments of sachets and envelopes as taught by the present inventionare depicted in FIGS. 6 through 11. The skilled artisan will appreciatethat intermediate rates of release can be accomplished by mixing andmatching different sachet layers and different envelope layers. Onlyroutine experimentation is required.

[0158] Another aspect of the present invention features a method offorming an apparatus for delivery of a gas. This method includes thesteps of: (a) providing a multi-layer structure comprising a reactantlayer centrally disposed between two sachet layers, and two envelopelayers disposed adjacent to the two sachet layers such that the twosachet layers are centrally disposed between the two envelope layers;and (b) stamping the multi-layer structure such that the two envelopelayers form an envelope defined about its perimeter by the stamp, andthe two sachet layers form a sachet defined about its perimeter by thestamp.

[0159] This method has many variations and embodiments. For example, asecond reactant layer disposed between an additional two sachet layerscan be included between the two envelope layers prior to step (a), sothat upon stamping, the apparatus includes two sachets, each with itsown reactant layer inside. Another variant adds the following steps tothe method described above: (c) providing an initiating agent in afrangible pouch and a second two envelope layers, (d) stamping thesecond two envelope layers to form a second envelope defined about itsperimeter by the stamp, such that the frangible pouch and the envelopeformed in step (b) are disposed within the second envelope.

[0160] Stamping includes any method of forming an envelope from theenvelope layers and a sachet from the sachet layers, e.g., sealing theperimeter with a glue or other sealant, impulse sealing and heatsealing.

[0161] This method is advantageous because it allows the apparatus ofthe present invention to be manufactured quickly and inexpensivelyrelative to assembling and forming each individual sachet and envelopeseparately.

[0162] In another aspect, the above method can be modified to constructan apparatus without an envelope. For example, the method can includesthe steps of: (a) providing a multi-layer structure comprising areactant layer centrally disposed between two sachet layers; and (b)stamping the multi-layer structure such that the two sachet layers forma sachet defined about its perimeter by the stamp.

[0163] Yet another aspect of the present invention features a method ofdelivering gas. This method includes the steps of: (a) providing anapparatus for delivery of a gas comprising an envelope, a sachetdisposed within the envelope, and a reactant disposed within the sachetthat generates a gas in the presence of an initiating agent, wherein theenvelope allows release of the gas from the envelope; and (b) disposingthe apparatus in an environment that comprises an initiating agent.

[0164] This method has many variations and embodiments. For example, theenvironment can be liquid and the initiating agent can be water or theenvironment can be gaseous and the initiating agent can be water vapor.Preferably, the water vapor is that naturally diffused in the gaseousenvironment, e.g., atmospheric water diffused in air at ambienttemperature.

[0165] In another aspect, the above method can be modified to includesthe steps of: (a) providing an apparatus for delivery of a gascomprising a sachet and a reactant disposed within the sachet thatgenerates a gas in the presence of an initiating agent; and (b)disposing the apparatus in an environment that comprises an initiatingagent.

[0166] Optionally, to further increase stability of any of the apparatusof the present invention during storage and shipment, any desiccant,such as silica gel or molecular sieves, can be used to scavengeinitiating agent prior to use of the apparatus.

[0167] Layered Apparatus

[0168]FIGS. 12A, 12B and 12C are an exploded view, a cross-sectionalside view, and a perspective view, respectively, of an exemplaryembodiment of an apparatus 510 constructed in accordance with thepresent invention. In general overview, apparatus 510 includes anenvelope layer 520, a sachet layer 530 disposed adjacent to the envelopelayer 520, a barrier layer 550 disposed adjacent to the sachet layer530, and reactant 540 disposed in the volume defined by the sachet layer530 and the barrier layer 550. The reactant 540 can generate a gas inthe presence of an initiating agent, e.g., water. Sachet layer 530 andenvelope layer 520, are permeable layers that allow passage of theinitiating agent to the reactant 540 and release of the gas from theapparatus 510. Barrier layer 550 is formed to define a cavity 554 toreceive reactant 540, and an edge 558 about its perimeter. The envelopelayer 520 and sachet layer 530 are fused about their perimeter along theedge 558 of barrier layer 550. Apparatus 510 is particularly useful forthe rapid release of a gas for wet applications.

[0169] Envelope layers are chosen to control the influx of theinitiating agent, while limiting the diffusion of the reactants to thesurrounding fluid, be it gaseous or liquid. The envelope layer alsoallows the gas generated by reactant to diffuse to the surroundingfluid, be it gaseous or liquid. By limiting transmission of theinitiating agent into the apparatus, and limiting and/or preventingdiffusion of the reactants out of the apparatus, the reactant remainsconcentrated and the pH of the reactive system is localized within theapparatus to optimize the conversion of reactant to gas. Additionally,intermediates and/or by-products of the reaction, e.g., water, also cancontribute to the efficiency and/or duration of the reaction by itsaffect on the equilibrium of the reactions.

[0170] Preferred envelope layers are described above for the embodimentsdepicted in FIGS. 1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B, 5A and 5B. An envelopelayer that is currently preferred for this embodiment is a hydrophobicpolypropylene copolymer film sold under the designation SM700 by SealedAir Corporation and has 330 holes per square inch having a diameter of0.4 mm, a 6.4% perforated area and a water vapor transmission rate of700 g/m²/24 hrs at 50% relative humidity. Also suitable is a hydrophobicpolypropylene copolymer film sold under the trade designation SM570 thathas 162 holes per square inch having a diameter of 0.4 mm mm, a 32%perforated area and a water vapor transmission rate of 570 g/m²/24 hrsat 50% relative humidity and also is available from Sealed AirCorporation. Also suitable for use as an envelope layer is thepolypropylene layer sold under the designation 060P1 by CunoIncorporated (Meriden, Conn.).

[0171] The sachet layer can be used to limit the diffusion of theinitiating agent into the volume defined by the sachet layer and thebarrier layer, and limit the diffusion of reactant and any reactionby-products out of the volume defined by the sachet layer and thebarrier layer. As a consequence, the reactant is and remainsconcentrated within the volume defined by the sachet layer and thebarrier layer and the pH remains localized increasing the efficiency ofthe reaction. Various attributes of the sachet layer, such as pore size,bubble point, and hydrophobic and/or hydrophilic nature of the sachet,can be manipulated to control the affect of the sachet layer on thereaction as is described above.

[0172] Preferred sachet layers are described above for the embodimentsdepicted in FIGS. 1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B, 5A and 5B. Sachetlayers that are currently preferred for this embodiment include anextruded, 0.65 micron pore size, hydrophilic polypropylene membrane soldunder the trade designation MPLC from Millipore (Bedford, Mass.). Alsosuitable for use as sachet layers are the nylon 6,6 membrane layers soldunder the designations 045ZN, 045ZY and 045ZL by Cuno Incorporated(Meriden, Conn.). The nylon 6,6 membrane layer sold under the tradedesignation 045ZY by Cuno Incorporated is currently preferred and has athickness of between about 180 to about 240 microns, a pore size ofabout 0.45 microns, and a bubble point of about 24.1 psi.

[0173] The barrier layer preferably is constructed of a material that isdurable and stable. Preferably, it is capable of being affixed to sachetlayers and envelope layers for fabrication purposes, e.g., so that thelayers can be fused about their perimeters to form a defined volume.Preferably, the impermeable layer has a water vapor transmission rate(WVTR) of less than about 50 g/m²/24 hrs at 70% relative humidity. Morepreferably, the impermeable layer has a water vapor transmission rate(WVTR) of less than about 2 g/m²/24 hrs at 70% relative humidity. Mostpreferably, the impermeable layer has a water vapor transmission rate(WVTR) of less than about 0.5 g/m²/24 hrs at 70% relative humidity.

[0174] Barrier layers can be constructed of various materials, includingmetals, polymeric material and/or coated papers. Other suitablematerials for forming barrier layers include, but are not limited to,polymeric layers constructed from, e.g., polyethylene, polypropylene,polyester, styrene, including polystyrene, polyethylene terephthalate,polyethylene terephthalate glycol (PETG), polyvinyl chloride,polyvinylidene chloride, ethylvinyl alcohol, polyvinyl alcohol,including polyvinyl alcohol acetate, acrylobutylstyrene and/orpolytetrafluoroethylene, polyacrylate and polyamide, including nylon.Also suitable are metallized layers, e.g., any of the above polymericlayers that have been metallized. Also suitable are metallic foils, suchas aluminum foils. Various other impermeable materials can be used toform the barrier film as well, such as glass or ceramics. In additionlayers that are composites of the above layers and/or laminates of theabove layers, e.g., paper/film/foil composites are also suitable for useas a barrier layer. One currently preferred impermeable layer is a 5 milthick impermeable layer comprising a polyester exterior, a metallizedbiaxially oriented core, and a polyethylene interior sealing layeravailable from Sealed Air Corporation (Duncan, S.C.). This layer has awater vapor transmission rate of 0.01 g/100 in²/24 hrs at 70% relativehumidity and 122° F. Another currently preferred impermeable layer isconstructed from polyvinyl chloride. Yet another currently preferredimpermeable layer is constructed from polyethylene terephthalate glycol(PETG).

[0175] The geometry and size of the barrier layer can be adapted to suitvarious parameters, including the amount and type of reactant, thedesired surface area of the sachet layer and/or envelope layer, andattachments for the storage and use of the apparatus. In one currentlypreferred embodiment, the barrier layer forms a cavity to receivereactant. It is also preferable that the barrier layer is formed suchthat it includes an edge about its perimeter for forming a seal with thesachet layer and/or envelope layer and/or second barrier layer. It isalso preferable that the barrier layer forms a cavity that, with the oneor more permeable layers, defines a volume that is the same or onlyslightly larger than the volume of the reactants. That is, it ispreferable to minimize reactant headspace in the apparatus of thepresent invention.

[0176] The barrier layer also can be formed into a shape such that theapparatus is easily inserted into or removed from various containers,such as a bottle or pouch. For example, it can be formed so that it canbe inserted into a cap, such as a bottle cap or pouch cap, so that thecap can then be attached, e.g., by a threaded seal, snap fit or pressurefit, to a receptacle for delivery of an initiating agent and/orreceiving the generated gas. One such exemplary embodiment is describedin greater detail in connection with FIGS. 16A and 16B below. Thebarrier layer also can be formed into various other geometries so thatit can be otherwise affixed to a container, such as to a bottle. Twosuch exemplary embodiments are described in greater detail in connectionwith FIGS. 15 and 18 below.

[0177] The barrier layer can be formed into various geometries byvarious manufacturing methods known in the art, including but notlimited to, horizontal form film seal, vertical form fill seal, blisterpack, skin pack, injection molding, blow molding, thermoforming, coldforming fill seal, or mechanical forming. Of course, the barrier layeralso may be flexible and not formed into any particular geometry, butsealed about its perimeter to the sachet about the reactant.

[0178] The envelope layer, sachet layer, and barrier layer of thepresent invention can be sealed about their perimeters by any knownmethod, such as heat sealing, ultrasonic sealing, radio frequencysealing, impulse sealing, and sealing with adhesives. Preferably, thelayers are fused with heat, by ultrasonic welding or by impulse sealing.

[0179] Reactant in general, preferred reactants, reactant ratios, andthe like, are described above for the embodiments depicted in FIGS. 1A,1B, 2A, 2B, 3A, 3B, 4A, 4B, 5A and 5B. Preferably, the reactant includesa stabilizer, such as activated hydrotalcite.

[0180] Optionally, in certain embodiments the reactant can furtherinclude a drying agent, or desiccant, to prevent premature initiation ofthe reactant. For example, desiccant can be added to the reactant toscavenge water vapor introduced during construction of the apparatusand/or shipping and storage of the apparatus, but in amounts smallenough such that it would not prevent initiation when desired. Suitabledesiccants include, for example, molecular sieves. Alternatively oradditionally, desiccant can be separately contained in a permeable layerand located adjacent to or within the apparatus of the present inventionto absorb or adsorb water vapor. One such exemplary embodiment isdescribed in greater detail in connection with FIG. 20 below.

[0181] The ratio of volume defined by the sachet layer and the barrierlayer to reactant volume also can be manipulated to control theconcentration of the reactants, intermediates, byproducts, etc. withinthe volume defined by the sachet layer and the barrier layer. Thisrelationship is described in above.

[0182]FIG. 13 is a cross-sectional side view of another exemplaryembodiment of apparatus 600 constructed in accordance with the presentinvention. In general overview, apparatus 600 includes an envelope layer620, a sachet layer 630 disposed adjacent to the envelope layer 620, abarrier layer 650 disposed adjacent to the sachet layer 630, reactant640 disposed in the volume defined by the sachet layer 630 and thebarrier layer 650, and a second barrier layer 660 disposed adjacent tothe envelope layer 620.

[0183] Sachet layer 630 and envelope layer 620, are permeable layersthat allow passage of the initiating agent to the reactant 640 andrelease of the gas from the apparatus 600. Barrier layer 650 is animpermeable layer that defines a cuboid cavity 654 to receive reactant640, and an edge 658 about its perimeter where the barrier layer 650 isattached to the sachet layer 630 and the envelope layer 620.

[0184] The second barrier layer 660 is sealed about its perimeter to theenvelope layer 620. Preferably, second barrier layer 660 is sealed tothe envelope layer 620 by a peelable seal where the seal strength issuch that the barrier layer 660 can be removed from the envelope layer620 without disrupting either the seal between envelope layer 620 andsachet layer 630, or the seal between sachet layer 630 and barrier layer650. Until the second barrier layer 660 is removed, it preventsinitiation of the reactant 640 because it prevents passage of theinitiating agent to the reactant 640. Second barrier film 660 can beused to prevent passage of the initiating agent into the apparatus whenit is not in use, e.g., during storage and shipping.

[0185] Apparatus 600 is particularly useful for applications where theapparatus 600 is likely to be stored and/or shipped in the presence ofinitiating agent, e.g., water vapor in the surrounding air. Apparatus600 also is particularly useful for applications where a relativelylarge amount of reactant is desired as cavity 654 is formed toaccommodate a relatively large amount of reactant. The two barrierlayers 650, 660 prevent initiation of the reactant 650 until the secondbarrier layer 660 is removed.

[0186] The envelope layer, sachet layer, and barrier layer can beconstructed from any of the materials described above in connection withthe embodiments depicted in FIGS. 1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B, 5A,5B, 12A, 12B and 12C. Reactant in general, preferred reactant, reactantratios, reactant volume and the like, are described above in connectionwith the embodiments depicted in 1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B, 5A, 5B,12A, 12B and 12C.

[0187] Optional second barrier layer 660 can be constructed from any ofthe materials described above in connection with the barrier layerdepicted in FIGS. 12A, 12B and 12C. Second barrier layer 660 also can beconstructed from the same or different materials used to construct thebarrier layer 650. Currently preferred second barrier layers includemetal foil, nylon layers, polyvinylidene chloride layers, ethylvinylalcohol layers and composites or laminate of these layers, such as ametallic foil/polyethylene layer laminate.

[0188] The second barrier layer can be sealed to the perimeter of theenvelope layer, or sachet layer if no envelope layer is used, using anyof the methods described above in connection with sealing the barrier,sachet layer and envelope layer of FIGS. 12A, 12B and 12C. Preferably,the second barrier layer is attached to the envelope layer by impulsesealing or heat sealing. Optionally, the second barrier layer also caninclude a device, such as a tab along its perimeter that facilitates itsremoval from the envelope layer without disrupting the other layers.

[0189]FIG. 14 is a cross-sectional side view of another exemplaryembodiment of apparatus 700 constructed in accordance with the presentinvention. In general overview, apparatus 700 includes an envelope layer720, a sachet layer 730 disposed adjacent to the envelope layer 720, abarrier layer 750 disposed adjacent to the sachet layer 730, reactant740 disposed in the volume defined by the sachet layer 730 and thebarrier layer 750, and a second barrier layer 760 disposed adjacent tothe envelope layer 720.

[0190] Sachet layer 730 and envelope layer 720, are permeable layersthat allow passage of the initiating agent to the reactant 740 andrelease of the gas from the apparatus 700. Barrier layer 750 is animpermeable layer that forms a hemispheroid cavity 754 to receivereactant 740, and an edge 758 about its perimeter where the barrierlayer 750 is attached to the sachet layer 730 and the envelope layer 720by a heat or impulse seal.

[0191] The second barrier layer 760 also is sealed about its perimeterto the envelope layer 720 by a heat or impulse seal. Preferably, secondbarrier layer 760 is sealed to the envelope layer 720 so that it can beremoved from the envelope layer 720 without disrupting the attachment ofthe envelope layer 720 to the sachet layer 730 and the sachet layer 730to the barrier layer 750. Until the second barrier layer 760 is removed,it prevents initiation of the reactant 740 because it prevents passageof the initiating agent to the reactant 740. Second barrier film 760 canbe used to prevent passage of the initiating agent into the apparatuswhen it is not in use, e.g., during storage and shipping.

[0192] Apparatus 700 is particularly useful for applications where theapparatus 700 is likely to be stored and/or shipped in an environmentthat allows contact of the initiating agent with the apparatus.Apparatus 700 also is particularly useful for applications where it isdesirable to utilize relatively small amounts of reactant to deliver gasto limited volumes of liquid. The two barrier layers 750, 760 preventinitiation of the reactant 740 until the second barrier layer 760 isremoved.

[0193] The envelope layer, sachet layer, and barrier layer can beconstructed from any of the materials described above in connection withFIGS. 1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B, 5A, 5B, 12A, 12B, 12C and 13.Reactant in general, preferred reactants, reactant ratios, and the like,are described above in connection with FIGS. 1A, 1B, 2A, 2B, 3A, 3B, 4A,4B, 5A, 5B, 12A, 12B, 12C and 13.

[0194] The second barrier layer can be constructed from any of thematerials described above in connection with the barrier layers depictedin FIGS. 12A, 12B, 12C and 13. The second barrier layer can be sealed tothe perimeter of the envelope layer, or sachet layer if no envelopelayer is used, using any of the methods described above in connectionwith sealing the barrier, sachet layer and envelope layer of FIGS. 12A,12B and 12C and 13. Preferably, it is heat or impulse sealed or sealedwith an adhesive. Optionally, the second barrier layer also can includea device, such as a tab along its perimeter that facilitates its removalfrom the envelope layer without disrupting the other layers (not shown).

[0195]FIG. 15 is a perspective view of still yet another exemplaryembodiment of an apparatus 870 constructed in accordance with thepresent invention. In general overview, apparatus 870 includes a pouch875 having a spout 880 and a cap 885, and apparatus 510 as described inconnection with FIGS. 12A, 12B and 12C. The apparatus 510 can be affixedto a wall of pouch 875, e.g., by adhesive or thermal bonding.Alternatively, it can be located within pouch 875 without being affixedthereto so that, e.g., it can be removed and replaced after use.

[0196] Apparatus 870 is particularly useful for the release of gas intoa desired amount of liquid, e.g., water or air, so that a desiredconcentration of the gas in the liquid can be easily achieved. Theamount of liquid can be defined by the volume of the pouch, pre-measuredbefore addition of the pouch, or the pouch can include indicia locatedon the wall of the pouch to indicate various volumes that can beoccupied by the liquid. The final concentration of the gas in the liquidcan be controlled by choice of, e.g., of reactant amount, reactantratio, sachet layer, and envelope layer, as described in connection withFIGS. 1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B, 5A, 5B, 12A, 12B, 12C, 13 and 14.

[0197] The pouch and cap can be constructed from any of the impermeableor permeable materials disclosed above in connection with FIGS. 12A,12B, 12C and 13-14. Preferably, the pouch and cap are constructed frompolypropylene, polyethylene, polyethylene terephthalate, metal foil,nylon and/or composites or laminates of these layers such as afoil/polyethylene laminate. The pouch can be constructed fromimpermeable materials to avoid introduction of initiating agent into thepouch prior to the desired initiation of the reactant, e.g., duringshipping and storage. One such pouch material suitable for use inaccordance with the present invention is constructed from a 5 mil thickimpermeable layer comprising a polyester exterior, a metallizedbiaxially oriented core, and a polyethylene interior sealing layer. Thislayer has a water vapor transmission rate of 0.01 g/100 in²/24 hours at70% relative humidity and 122° F. Alternatively or additionally, theapparatus 510 can further include a second barrier film as described inFIGS. 13 and 14.

[0198] The apparatus 870 can be used by filling the pouch 875 with aliquid that includes initiating agent, attaching the cap 885 to thespout 880, and awaiting the generation of the desired quantity of gas byapparatus 510 into the liquid contained within the pouch 875. Thisembodiment can be useful for preparing solutions for removing biofilmand/or sanitizing plastic waterlines in dental, marine or aerospaceapplications. This embodiment can also be useful for preparing solutionsfor surface sanitation, infection control and the like. Alternatively,any other water reservoir, such as a rigid bottle may be used instead ofthe pouch.

[0199]FIGS. 16A and 16B are a perspective view and an enlargedcross-sectional side view of a portion, respectively, of yet anotherexemplary embodiment of an apparatus 972 constructed in accordance withthe present invention. In general overview, the apparatus 972 includes apouch 975, a spout 980, and a cap 985. The cap 985 includes a barrierlayer 950, reactant 940, a sachet layer 930 and an envelope layer 920.The barrier layer 950 is formed to define a cavity to receive reactant940 and also is formed to fit into cap wall 990. The barrier layer 950is attached to the cap wall 990 by snap in pressure fit so that it staysin position and can be removed and replaced after generation and releaseof the gas. Cap wall 990 defines an interior thread 994 that matchesexterior thread 996 defined by spout 980. Spout 980 further includes asecond barrier film 995 that seals the opening defined by the spout 980.

[0200] Apparatus 972 is particularly useful for preparing solutions forremoving biofilm and sanitizing plastic waterlines in dental, marine,beverage and aerospace applications. This embodiment also can be usefulfor preparing solutions for surface sanitation, infection control andthe like. One advantage of this embodiment is that the barrier films950, 995 prevent initiation of the reactant when not in use, e.g.,during shipping and storage, by sealing the apparatus by threading thecap to the spout in an environment substantially free from initiatingagent and not removing the cap until initiation is desired. Whengeneration of gas is desired, the cap can then be removed from thespout, and the second barrier film removed from the spout. The pouch canthen be filled with liquid in part or entirely, the cap replaced and thereaction initiated, such that gas is released and enters the pouch.

[0201] Apparatus 972 also is advantageous because the pouch need not beconstructed from impermeable materials, because the second barrier filmprevents initiation of reaction when not in use, e.g., during storageand shipment.

[0202] The envelope layer, sachet layer, barrier layers, pouch and capcan be constructed from any of the materials are described in connectionwith FIGS. 1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B, 5A, 5B, 12A, 12B, 12C, 13, 14and 15. Reactant in general, preferred reactants, reactant ratios, andthe like, also are described in connection with FIGS. 1A, 1B, 2A, 2B,3A, 3B, 4A, 4B, 5A, 5B, 12A, 12B, 12C, 13, 14 and 15. The cap can besealed by other means known in the art, e.g., by a pressure fitting.

[0203] Optionally, a barrier film can be placed on the opening definedby the cap wall. Thus, the cap can be stored and shipped separately fromthe pouch. This can be advantageous, e.g., in applications where thepouches can be reused, and thus material costs, storage space, storagecosts, and shipping costs can be reduced. Alternatively, any other waterreservoir, such as a rigid bottle may be used instead of the pouchdepicted in FIGS. 16A and 16B.

[0204]FIGS. 17A and 17B are a cross-sectional side view and aperspective view, respectively, of still yet another exemplaryembodiment of apparatus 1000 constructed in accordance with the presentinvention. In general overview, apparatus 1000 includes a sachet layer1035, a barrier layer 1050 disposed adjacent to the sachet layer 1035,and reactant 1040 disposed in the volume defined by the sachet layer1035 and the barrier layer 1050. Sachet layer 1035 is a permeable layer.Barrier layer 1050 is an impermeable layer and defines a cavity 1054 andan edge 1058 about its perimeter.

[0205] Apparatus 1000 is particularly useful for applications where theperformance of the apparatus without an envelope layer is sufficientbecause production is simplified as the step of constructing theenvelope layer is eliminated. In addition, eliminating the need toprovide an envelope layer to construct the apparatus can decreasematerial costs.

[0206] The sachet layer and barrier layer can be constructed from any ofthe materials described in connection with FIGS. 1A, 1B, 2A, 2B, 3A, 3B,4A, 4B, 5A, 5B, 12A, 12B, 12C, 13, 14, 15, 16A and 16B. Preferably, thesachet layer is constructed using a hydrophobic membrane so that thesachet layer limits the amount of water entering the apparatus. Acurrently preferred embodiment is an apparatus where the sachet layer isconstructed from a 0.65 micron pore size, hydrophobic polypropylenemembrane sold under the trade designation DOHP by Millipore (Bedford,Mass.). Another currently preferred embodiment is an apparatus where thesachet layer is constructed from a polypropylene layer sold under thetrade designation 060P1 by Cuno Incorporated (Meriden, Conn.).

[0207] Reactant in general, preferred reactants, reactant ratios, andthe like, are described in connection with FIGS. 1A, 1B, 2A, 2B, 3A, 3B,4A, 4B, 5A, 5B, 12A, 12B, 12C, 13, 14, 15, 16A and 16B.

[0208]FIG. 18 is a cross-sectional side view of still yet anotherexemplary embodiment of an apparatus 1104 constructed in accordance withthe present invention. In general overview, apparatus 1104 includes atubular bottle 1106, a pump mechanism 1112 in threaded connection withthe tubular bottle 1106 on a first end, a detachable portion 1124 inthreaded connection with the tubular bottle 1106 on a second end, andinsert 1132.

[0209] The bottle 1106 forms a spout 1108 that forms an exterior thread1109 on the first end that attaches to the pump mechanism 1112 fixed inscrew cap 1114 that forms a matching interior thread 1111. The bottle1106 also defines an opening 1118 on the second end and exterior thread1122 for attachment to the matching, interior thread 1126 defined bydetachable portion 1124. Detachable portion 1124 also is formed todefine a ridge 1128 about its interior perimeter that receives theinsert 1132.

[0210] Insert 1132 includes a barrier layer 1150, reactant 1140, asachet layer 1130, and an envelope layer 1120. The barrier layer 1150 isformed to snap into ridge 1128 and form a pressure fit so that it willremain in place during use and after use can be removed and replacedwith another similarly configured insert. The barrier layer 1150 also isformed to define a cavity 1154 to receive reactant 1140 and an edge 1158about its perimeter for attachment to the sachet layer 1130 and theenvelope layer 1120. Optionally, insert 1132 can further include asecond barrier layer adjacent to the envelope layer 1120 (not shown) asdescribed in connection with FIGS. 13 and 14.

[0211] Pump mechanism 1112 includes tubular plunger 1133 on whichpushbutton 1131 is mounted containing a spray nozzle 1134. Also shownare basic components of a typical pump, such as piston 1135, cylindricalchamber 1136, one-way valve 1137, collar 1138, and intake tube 1139.Alternate pump mechanisms are known in the art, such as the mechanismsdescribed in U.S. Pat. No. 4,077,549.

[0212] Apparatus 1104 is particularly useful for use in generating adesired concentration of gas in a liquid, e.g., water, that can then beeasily delivered to a desired location, e.g., a countertop fordisinfection, via a pump mechanism. The pump mechanism can be removedfrom the spout so that the volume defined by the tubular bottle anddetachable portion can be filled, partially or entirely, with a liquid,e.g., water. Detachable portion can be removed to attach or replace theinsert 1132, so that bottle 1106, pump mechanism 1112, and detachableportion 1124 can be reused.

[0213] The envelope layer, sachet layer, and barrier layer can beconstructed from any of the materials are described in connection withFIGS. 1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B, 5A, 5B, 12A, 12B, 12C, 13, 14, 15,16A, 16B, 17A and 17B. Reactant in general, preferred reactants,reactant ratios, and the like, are described in connection with FIGS.1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B, 5A, 5B, 12A, 12B, 12C, 13, 14, 15, 16A,16B, 17A and 17B.

[0214] The tubular bottle and the detachable portion can be constructedfrom any material described in connection with the pouch and capdescribed in FIGS. 15, 16A and 16B. The tubular bottle can be formed byany method known in the art, e.g., blow molding or injection molding.Pump mechanism 1112 can be any pump mechanism known in the art. A widevariety of pump mechanisms are commercially available.

[0215]FIG. 20 is a cross-sectional side view of another exemplaryembodiment of apparatus 1310 constructed in accordance with the presentinvention. In general overview, apparatus 1310 includes an envelopelayer 1320, a sachet layer 1330 disposed adjacent to the envelope layer1320, a barrier layer 1350 disposed adjacent to the sachet layer 1330,reactant 1340 disposed in the volume 1354 defined by the sachet layer1330 and the barrier layer 1350, and desiccant 1341 disposed in thevolume 1355 defined by the sachet layer 1330 and the barrier layer 1350.

[0216] Sachet layer 1330 and envelope layer 1320, are permeable layersthat allow passage of the initiating agent to the reactant 1340 andrelease of the gas from the apparatus 1310. Barrier layer 1350 is animpermeable layer that forms cavities 1354, 1355 to receive reactant1340 and desiccant 1341, respectively. The barrier layer 1350 isattached to the sachet layer 1330 and the envelope layer 1320 by a heator impulse seal about the perimeter of the cavities 1354, 1355.Optionally a second barrier layer (not shown) can be sealed about itsperimeter adjacent to the envelope layer 1320. Desiccant 1341 can beused to attract any ambient water vapor and/or liquid water and therebyprevent or minimize passage of water vapor and/or liquid water to thereactant 1340 disposed in cavity 1354 during storage and shipping.

[0217] This embodiment is particularly useful for wet applications andis more resistant to premature initiation than, e.g., the embodimentdepicted in FIGS. 12A, 12B and 12C, due to the presence of thedesiccant.

[0218] The envelope layer, sachet layer, barrier layer, and reactant canbe any of those described in connection with the above FIGS. 1A, 1B, 2A,2B, 3A, 3B, 4A, 4B, 5A, 5B, 12A, 12B, 12C, 13, 14, 15, 16A, 16B, 17A,17B, 18 and 19. In a currently preferred embodiment, the envelope layeris a hydrophobic polypropylene copolymer film sold under the designationSM700 by Sealed Air Corporation and has 330 holes per square inch havinga diameter of 0.4 mm, a 6.4% perforated area, a thickness of about 20microns, and a water vapor transmission rate of 700 g/m²/24 hrs, thesachet layer is extruded, 0.65 micron pore size, hydrophilicpolypropylene membrane sold under the trade designation MPLC fromMillipore (Bedford, Mass.) or Nylon 6,6 membrane layer sold under thetrade designation 045ZY by Cuno Incorporated having a thickness ofbetween about 180 to about 240 microns, a pore size of about 0.45microns, and a bubble point of about 24.1 psi, the barrier layer is apolyethylene terephthalate glycol (PETG) or polyvinyl chloride (PVC)layer, the reactant includes sodium chlorite and citric acid, and thedesiccant comprises molecular sieves.

[0219] Apparatus 1310 can also be incorporated into a pouch like thatdepicted in FIG. 15 to generate a desired concentration of gas, e.g.,chlorine dioxide, in water. This embodiment is particularly useful inwet applications, e.g., for use in removing biofilm from dentalequipment. One such apparatus was constructed and used to generate anaqueous solution containing 50 parts per million chlorine dioxide. Itwas then emptied into a dental equipment reservoir and allowed to runthrough the equipment, which was contaminated with biolfilm, and standovernight. In the morning, the dental equipment was flushed with water.This procedure was repeated the following two nights. The equipment wasthen tested for the presence of biofilm and the biofilm was diminished.Thereafter, rinsing the equipment once daily with a 5 parts per millionsolution was adequate to retard the growth of biofilm in the equipment.

[0220] In view of the collective teachings and guidance set forthherein, the practitioner can design, fabricate, test and use any numberof embodiments of the present invention. All that is required is anordinary level of skill in the art and some routine experimentation.

[0221] Another aspect of the present invention features a method offorming an apparatus for delivery of a gas. This method includes thesteps of: (a) providing a multi-layer structure comprising a reactantlayer centrally disposed between a sachet layer and a barrier layer, andan envelope layer disposed adjacent to the sachet layer; and (b) sealingthe perimeter of the barrier layer, sachet layer and barrier layer suchthat the reactant is disposed in a volume defined by the sachet layerand the barrier layer.

[0222] This method has many variations and embodiments. For example, asecond barrier layer can be disposed adjacent to the envelope layeropposite the sachet layer prior to step (a). Another example is that instep (b) the seal can be effected by adhesive and/or by stamping themulti-layer structure with a hot die to heat-seal the layers together.

[0223] Sealing includes any method of substantially sealing the envelopelayer, the sachet layer and the barrier layer about their perimeters,e.g., sealing the perimeter with a glue or other sealant, impulsesealing, ultrasonic sealing and heat sealing.

[0224] In a preferred embodiment, the apparatus is manufactured in anarray for ease of manufacturing. This method includes: (a) providing alayer of impermeable material that has an array of cavities formedtherein; (b) disposing reactant in the array of cavities; (c) disposingone or more permeable layer over the layer of impermeable material; (d)sealing the one or more permeable layers to the layer of impermeablematerial about the perimeter of each cavity; and (e) cutting theimpermeable material and the one or more permeable materials about theperimeter of each cavity.

[0225] This method is advantageous because it allows the apparatus ofthe present invention to be manufactured quickly and inexpensivelyrelative to assembling and forming each individual sachet and envelopeseparately and/or manually.

[0226] The impermeable material provided in step (a) can have an arrayof cavities formed therein, e.g., by using a thermoforming process toform the array of cavities. Thermoform machines suitable for use inaccordance with the present invention include those manufactured byMultivac (Kansas City, Mo.), Tiromat (Avon, Mass.) Robert Reiser & Co.(Canton, Mass.), and Ulma Packaging (Woodstock, Ga.). Other suitablemethods for forming the array of cavities include vacuum forming, coldforming, mechanical forming, and blister or skin packing process. Thereactant can be disposed in the array of cavities on an assembly lineand the one or more permeable layers can be sequentially positioned overthe impermeable material, e.g., by unwinding sheets of the one or morepermeable layers over the impermeable layer on an assembly line. The oneor more permeable layers can then be sealed to the impermeable materialabout the perimeter of each cavity using methods known in the art, e.g.,adhesives, heat sealing methods, ultrasonic sealing methods, radiofrequency sealing methods or impulse sealing. The impermeable materialand the one or more permeable materials can then be cut about theperimeter of each cavity using methods known in the art, e.g., by usinga die, to form an apparatus similar to those depicted in FIGS. 12A, 12B,12C, 13-15, 16A, 16B, 17A, 17B, 18 and 20.

[0227] These apparatus can then be inserted into the spout of a pouchthat has been otherwise sealed about its periphery. Alternatively, itcan be inserted into a pouch that has not been sealed about itsperiphery and the periphery then sealed, e.g., by using adhesive, heatsealing methods, ultrasonic sealing methods, radio frequency sealingmethods or impulse sealing methods. Optionally, the apparatus can beattached to a wall of the pouch, e.g., by using adhesive, heat sealingmethods, ultrasonic scaling methods, radio frequency scaling methods orimpulse sealing methods.

[0228] In another aspect, the above method can be modified to constructan apparatus without an envelope. For example, the method can includethe steps of: (a) providing a multi-layer structure comprising areactant layer centrally disposed between a sachet layer and a barrierlayer; and (b) sealing the multi-layer structure such that the such thatthe reactant is disposed in a volume defined by the sachet layer and thebarrier layer

[0229] Yet another aspect of the present invention features a method ofdelivering gas. This method includes the steps of: (a) providing anapparatus for delivery of a gas comprising an envelope layer, a sachetlayer disposed adjacent to the envelope layer, a barrier layer disposedadjacent to the sachet layer, and a reactant disposed in a volumedefined by the sachet layer and the barrier layer; and (b) disposing theapparatus in an environment that comprises an initiating agent.

[0230] This method has many variations and embodiments. For example, theenvironment can be liquid and the initiating agent can be water or theenvironment can be gaseous and the initiating agent can be water vapor.The apparatus can further comprise a pouch that can be filled with adesired liquid to receive the gas generated.

[0231] Optionally, to further increase stability of any of the apparatusof the present invention during storage and shipment, any desiccant,such as silica gel or molecular sieves, can be incorporated within theapparatus to scavenge initiating agent prior to use of the apparatus.

[0232] The present invention is useful for fabrication of a gas deliveryapparatus that is compact, cost-effective and safe. Furthermore, thepresent invention can be used for a variety of applications, includingdelivery of gas to air or water, for a variety of purposes includingremoval of biofilm, disinfection, deodorization, bleaching andsanitation.

[0233] As a general rule and without wishing to be confined to anytheory, it is expected that the amount and rate of gas release exhibitedby apparatus of the present invention will be influenced by the totalsurface area of the permeable layer adjacent to the reactant, but not bythe geometry of the apparatus. That is, the various embodiments of thepresent invention are expected to release the same volume of gas at thesame rate provided that the total surface area of the permeable layeradjacent to the reactant is about equal, all other variables being heldconstant. It has been discovered that hydrotalcite, and the metalhydroxides in the hydrotalcite family, can be used to stabilize one ormore reactants of the present invention. For example, hydrotalcite,including activated hydrotalcite, and metal hydroxides in thehydrotalcite family can be used to stabilized the following reactantsand combination of these reactants: acids, aqueous acids, citric acid,oxalic acid, fumaric acid, phosphoric acid, potassium bitartate,chlorites, chlorates, sulfites, bisulfites, sulfates, carbonate,nitrites. While not wishing to be bound to any particular theory, it isbelieved that the basic nature and ability to attract and bind water andwater vapor of hydrotalcite and its family members contribute to itsability to stabilize the reactants of the present invention. Basicadditives are less likely to react with chlorites and other reactantsthat react with acid than acidic additives. In addition, the ability ofhydrotalcite and its family members to attract, absorb, adsorb and/orotherwise bind water and water vapor mitigates or prevents prematureinitiation, e.g., during manufacture, shipping, and storage. The abilityof hydrotalcite to function as a flow agent also is desirable because itrenders the reactants more readily metered and dispensed duringmanufacture. Activated hydrotalcite, i.e., hydrotalcite that has beenheated drive off water, has been found to stabilize reactants in anapparatus such as those described in Examples 12 and 13 for at least sixmonths. The apparatus are expected to have a shelf life of at least ayear.

[0234] The mineral commonly known as hydrotalcite is the naturallyoccurring form of hydrotalcite, which has the chemical formula:Mg₆Al₂(OH)₁₆CO₃.4H₂O. Hydrotalcite, suitable for use in the apparatus ofthe present invention, is commercially available from DIP ChemicalIndustries (Mumbai, India). When activated, this hydrotalcite ishygroscopic, in that it absorbs water vapor up to about 36% of itsweight when exposed to about 97% relative humidity, and has a surface pHbetween about 11 and about 12. The hydrotalcite can be activated usingknown methods, e.g., by exposing it to high temperatures for an extendedperiod of time, e.g., 500° C. for one hour, and thereafter sealing thehydrotalcite in a low humidity environment so that it doesn't deactivateprematurely.

[0235] There also are metal hydroxides in the hydrotalcite family thatcan be used to stabilize reactants in accordance with the presentinvention. The family can be described with the general formula:A_(w)B_(x)(OH)_(y)C_(z).nH₂O, wherein A is a divalent metal cation, B isa trivalent metal cation, and C is a monovalent, divalent, trivalent, ortetravalent anion. The values for w, x, y, z, and n have the followingrelationship: 0 ≦z≦x≦4≦w≦{fraction (1/2)}y, and 12≧n≧{fraction (3/2)}x.Metal cations represented by A include, but are not limited to, Mg²⁺,Ni²⁺, Fe²⁺, and Zn²⁺. Metal cations represented by B include, but arenot limited to, Al³⁺, Fe³⁺, and Cr³⁺. Chemical species represented by Cinclude, but are not limited to CO₃ ²⁻, SO₄ ²⁻, OH⁻, NO₃ ⁻, and Cl⁻. Onesuch hydrotalcite is a hydrotalcite having the formula:Mg₄Al₂(OH)₁₂CO₃.nH₂O, and is commercially available from Alcoa WorldChemicals (Leetsdale, Pa.). Other suitable minerals in the hydrotalcitefamily include pyroaurite having the formula Mg₆Fe³⁺ ₂(OH)₁₆CO₃.4H₂O,and takovite having the formulaNi₆Al₂(OH)₁₆[(CO₃)_(0.75)(OH)_(0.25)].4H₂O. Preferably, the hydrotalciteis added to the reactant such that the resulting mixture is betweenabout 1% and about 25% hydrotalcite by weight. More preferably, theresulting mixture is between about 5% and about 20% hydrotalcite byweight.

[0236] Another aspect of the present invention is an apparatus fordelivery of a gas including a sachet that includes a material that iswater vapor selective, and a reactant disposed in the sachet thatgenerates a gas in the presence of an initiating agent. The term “watervapor selective” as used herein refers to a material that selectivelyallows permeation of water vapor and substantially impedes permeation ofliquid water. More preferably, the material excludes permeation ofliquid water. Typically, the water vapor selective material ishydrophobic. The skilled practitioner typically refers to water vaporselective material as water impermeable, although water vapor canpermeate the layer, and refers to materials that allow permeation ofliquid water as water permeable. Suitable water vapor selectivematerials can be made from a variety of materials including, but notlimited to, polytetrafluoroethylene (PTFE), polypropylene (PP),polyethylene (PE), and fluorinated ethylene propylene (FEP).

[0237] Water vapor selective material also is particularly advantageousbecause it substantially impedes or excludes the diffusion of watersoluble species, such as water soluble reactants, additives, andreaction by-products, out of the apparatus. Membranes that allow liquidwater permeation allow soluble species such as soluble reactants topermeate the apparatus and enter the environment. Prior attempts havebeen made to ameliorate or avoid escape of soluble species by usinginsoluble reactants or by binding or otherwise disposing the solublespecies on insoluble materials such as clays and molecular sieves. Thisis not advantageous because it introduces additional steps and/orexpense to the preparation of the apparatus. Thus, the water vaporselective materials of the present invention are advantageous becausethey impede or preclude the permeation of the soluble reactants,additives, and by-products, thus removing the need to include orgenerate insoluble reactants, by-products and/or additives.

[0238] Water vapor selective materials also are advantageous becausetheir use eliminates the need to use any further layers, e.g., furthersachet and/or envelope layers, to retain soluble species in theapparatus, which also introduces additional steps and expense in theconstruction of the apparatus.

[0239] Preferably, the water vapor selective material has a thicknessbetween about 5 microns and about 400 microns thick, a pore size betweenabout 0.05 microns and about 10 microns, and a water intrusion pressurebetween about 30 millibars and about 4,000 millibars. Preferably, thewater vapor selective material is adhered to or otherwise supported by asupport layer that allows liquid water to permeate the support layer,and the overall thickness of both the water vapor selective layer andthe support layer is between about 1 mil and 20 mils. More preferred,are water vapor selective materials having a thickness between about 15microns and about 200 microns thick, a pore size between about 0.25microns and about 5 microns, and a water intrusion pressure betweenabout 100 millibars and about 1,500 millibars. Preferably this layer hasa water permeable support layer such that the total thickness of bothlayers is between about 2 mils and about 10 mils. Most preferred, arewater vapor selective materials having a thickness between about 20microns and about 100 microns thick, a pore size between about 1 micronand about 3 microns, and a water intrusion pressure between about 200millibars and about 750 millibars. Preferably this layer has a waterpermeable support layer such that the total thickness of both layers isbetween about 3 mils and about 8 mils.

[0240] Generally, if rapid generation and release of gas is desired, athinner layer is preferred because the thinner the layer, the morerapidly water vapor can diffuse into the apparatus and initiate thereaction, and the more rapidly gas can diffuse out of the apparatus.Conversely, if slower generation and release of gas is desired a thickermaterial is preferred, such as between about 5 mils and about 20 mils.Additionally or alternatively, if slower generation and release of gasis desired, a relatively smaller surface area of the material can beused. For example, a sachet including a rigid frame can be used toconstruct the sachet as described below and illustrated in Example 15,and one or both sachet layers can be constructed from a water vaporselective material.

[0241] Additionally or alternatively, pore size of the water vaporselective layer can be selected to produce the desired release atspecific depths of water in which the apparatus will be used. A smallerpore size will correspond to deeper operation by increasing the amountof hydraulic water pressure that the membrane will experience whileremaining impermeable to liquid water.

[0242] Water vapor selective layers suitable for use in constructing theapparatus of the present invention preferably have water vaporpermeability of between about 2,000 g/m²/24 hrs and about 150,000g/m²/24 hrs, as determined by JIS L 1099-1985 (Method B), “TestingMethods for Water Vapour Permeability of Clothes,” from the JapaneseStandards Association. Water vapor selective layers preferably have aresistance to liquid water permeation of at least about 30 millibars asdetermined by ISO 811-1981 “Textile fabrics—Determination of resistanceto water penetration—Hydrostatic pressure test” published by theInternational Organization for Standardization.

[0243] Optionally, the water vapor selective layer or layers of thepresent invention can include a support layer to increase the strengthof the layer, and/or to increase its ability to bond to the othermaterials used to construct the apparatus. The support layer preferablyallows diffusion or passage of initiating agent to the surface of thewater vapor selective layer. For example, the support layer can be spun,perforated or have large pores that allow passage of liquid water andvapor to the surface of the water vapor selective layer. The supportlayer can be affixed to the water vapor selective layer by any means,for example, lamination, casting, co-extrusion, and/or adhesive layers.Preferably, the sachet is constructed so that the water vapor selectivelayer faces the interior of the sachet. The support layer itself can behydrophilic and/or hydrophobic. If hydrophilic, the material can be usedto attract and deliver liquid water and/or vapor to the surface of thewater vapor selective material. Suitable support layers include, but arenot limited to, polyethylene, polypropylene, nylon, acrylic, fiberglass,and polyester in the form of woven, non-woven, and mesh layers.Preferably, the support layer thickness is between about 1 mil and 20mils.

[0244] Suitable water vapor selective materials previously describedherein include the 0.60 pore size, hydrophobic, polypropylene (PP)membrane having a thickness between about 250 microns and about 300microns sold under the designation 060P1 by Cuno Incorporated (Meriden,Conn.). Also suitable is the 0.65 micron pore size, hydrophobicpolyethylene material sold under the trade designation DOHP by Millipore(Bedford, Mass.)

[0245] Another water vapor selective material, suitable for use in arapid release apparatus, includes a 1.75 mil thick, hydrophobicpolytetrafluoroethylene (PTFE) layer thermally bonded to a 5 mil thick,hydrophobic polyethylene (PE) support layer sold under the tradedesignation BHA-TEX® by BHA Technologies (Kansas City, Mo.). Itsresistance to liquid water permeation is at least about 500 millibar.

[0246]FIG. 21 is a perspective view of yet another exemplary embodimentof an apparatus 1510 constructed in accordance with the presentinvention. Apparatus 1510 includes a sachet layer 1535, an intermediatelayer 1570 disposed adjacent the sachet layer 1535, and a barrier layer1550 disposed adjacent the intermediate layer 1570. A first reactant1540 is disposed in the volume defined by the barrier layer 1550 and theintermediate layer 1570, and a second reactant 1544 is disposed in thevolume defined by the intermediate layer 1570 and the sachet layer 1535.

[0247] The sachet layer can be constructed from any of the layersdescribed above. Preferably, the sachet layer includes a water vaporselective layer and an adjacent support layer. The first reactant andthe second reactant can be any of the reactants described above. Thereactant or reactants can further include additives, such as activatedhydrotalcite. The intermediate layer can be constructed of any of thelayers described above. Preferably, the intermediate layer comprises acellulose layer such as the Japanese paper “Tosa Tengujo” sold byBookmakers (Hagerstown, Md.). The barrier layer can include any of thebarrier layers describe above. In a preferred embodiment the barrierlayer is constructed from a composite of a metalized bi-axially orientedpolypropylene about 1 mil thick and a linear low density polyethyleneabout 4 mils thick. This apparatus is advantageous because it can beconstructed by placing sheets of the sachet, intermediate, and barrierlayers adjacent each other and sealing about the edges and cutting aboutthe seal in one step. Optionally, a portion of the apparatus can be leftunsealed until the volumes defined by the layers are filled withreactant and then sealed. Alternatively, the reactant can be layeredwith the layers and the entire periphery of the layers sealed at once.

[0248] Sachets Including a Rigid Frame

[0249] In another aspect of the invention, the apparatus includes asachet that includes a rigid frame defining at least one opening and asachet layer disposed about the opening such that a volume is defined bythe sachet. The rigid frame can be a rigid barrier layer as describedabove. The rigid frame also can take the form of a tubular member thatcan have any shape, such as a circular, oval, rectangular, orsquare-shaped cross section along the tube. If the rigid frame istubular, at least one end preferably has a sachet layer disposed aboutit. A second sachet layer may be disposed about a second end of therigid frame. Additionally or alternatively, any other layer that willdefine a closed receptacle for reactant, such as a barrier layer, can bedisposed about a second end. Yet another option is to have a detachablemember on the second end such as a threaded cap that can be removed,e.g., to remove and/or replace reactant and any additional sachetswithin the sachet. Sachets including rigid frames are advantageousbecause they can be fit into various devices, e.g., a humidifier, filteror cartridge. They also can be dropped in a reservoir and, depending onthe materials used to construct the rigid frame, can sink to the bottomof a solution, e.g., if made with PVC, or float on top, e.g., ifconstructed with a foamed material. The apparatus can further includeweighted materials to increase its tendency to reside at a bottom of areservoir. The sachet includes one or more reactants that generate a gasin the presence of the initiating agent. The reactants can be mixed orseparated by further structures, such as an additional sachet or anintermediate layer within the sachet as described herein.

[0250]FIGS. 22A and 22B are a perspective and cross-sectional side view,respectively, of an exemplary embodiment of an apparatus 1600 includinga sachet constructed in part with a rigid frame. The apparatus 1600,includes a first sachet 1610, a second sachet 1620, a first reactant1630, and a second reactant 1640. The first sachet is constructed from arigid frame 1614 that is cylindrical in shape and two sachet layers1616, 1618 disposed on either side of the rigid frame 1614 such that therigid frame 1614 and the sachet layers 1616, 1618 define a closedreceptacle for reactant. The first reactant 1630 is disposed in thefirst sachet 1610, but not within the second sachet 1620. The secondreactant 1640 is disposed within the second sachet 1620. Thus, the firstreactant 1630 is separated from the second reactant 1640 by the secondsachet 1620.

[0251] The rigid frame can be constructed from any rigid materials suchas the barrier materials described above. For example, the rigidmaterials can include polyvinylchloride, polyethylene, polypropylene,polyester, styrene, polystyrene, polyethylene terephthalate,polyethylene terephthalate glycol, acrylobutylstyrene, polyacrylate,nylon, polyamide, and combinations thereof. The reactants can be any ofthe reactants described above. The reactants can be mixed or separatedin separate volumes, e.g., sodium chlorite can be disposed in the firstsachet and citric acid in the second sachet. Optionally the reactantscan include additives. Preferably, one or more of the reactants is mixedwith activated hydrotalcite.

[0252] The sachet layers can be constructed from any of the sachetmaterials described herein. For example, the sachet layers can beconstructed from a water vapor selective material, e.g., a PTFE/PE layeras described above. The sachet layers can also be constructed from alayer that initially allows entry of water but subsequently impedes thepassage of water. Without wishing to be bound to any particular theory,it is believed that the layer swells upon introduction of water to thelayer and that the layer allows passage of water until the layer swellsto such an extent that water can no longer pass through the pores. In acurrently preferred embodiment, the first sachet layer is constructedfrom a water vapor selective material, the second sachet layer isconstructed from a layer that initially allows entry of water butsubsequently impedes the passage of water, and the rigid layer isinjection molded PVC.

[0253] The apparatus can further include additional sachet layers and/orenvelope layers adjacent the first and second sachet layers (not shown).The additional sachet layers and envelope layers can be constructed ofany of the materials described herein. The first and second reactant canbe any of the reactants described herein. The apparatus can furtherinclude additional sachets, envelopes, and/or reactant additives, suchas desiccants, stabilizers and the like as described above. Whilepreferred, the second sachet is optional and the reactants need not beseparated in any manner.

[0254]FIGS. 23A and 23B are a perspective and cross-sectional side view,respectively, of another exemplary embodiment of an apparatus 1700including a sachet constructed in part with a rigid frame. The apparatus1700, includes a sachet 1710, an intermediate layer 1750, a firstreactant 1730, and a second reactant 1740. The sachet 1710 isconstructed from a rigid frame 1714 having a square cross-section andtwo sachet layers 1716, 1718 disposed on either side of the rigid frame1714 such that the rigid frame 1714 and the sachet layers 1716, 1718define a closed receptacle for reactant. The rigid frame 1714 isbisected by the intermediate layer 1750, which defines a first volume1754, and a second volume 1758. The first reactant 1730 is disposed inthe first volume 1754, and the second reactant 1740 is disposed in thesecond volume 1758. Thus, first reactant 1730 is separated from secondreactant 1740 by the intermediate layer. The apparatus 1700 furtherincludes a first envelope layer 1760 disposed adjacent the first sachetlayer 1716, and a second envelope layer 1764 adjacent the second sachetlayer 1718.

[0255] The rigid frame, sachet layers, and envelope layers can beconstructed from any of the materials described herein. For example, therigid frame can be constructed from PVC, and the sachet layers can beconstructed from a water vapor selective material. Optionally, one ormore of the sachet layers can be constructed from a layer that initiallyallows entry of water but then impedes the passage of water. Theapparatus can further include additional sachet layers and/or envelopelayers adjacent the first and second sachet layers (not shown). Theadditional sachet layers and envelope layers can be constructed of anyof the materials described herein. The first and second reactant can beany of the reactants described herein. The apparatus can further includeadditional sachets, envelopes, and/or reactant additives, such asdesiccants, stabilizers and the like as described above. Whilepreferred, the second sachet is optional and the reactants need not beseparated in any manner.

[0256] Sachets including a rigid frame can be constructed by any of themethod described herein, e.g., by adhesives and/or heat sealing thesachet layers, and optionally envelope layers, to the rigid frame.Additional sachets and/or enveloped within or about the sachet includingthe rigid frame can be constructed by any method known in the artincluding those described herein. The intermediate layer and the rigidframe portions also can be attached by any of the methods describedherein. Apparatus including such sachets can be used in any applicationsdescribed herein, including, but not limited to, use in a conduit,humidifier, and in both wet or dry applications.

[0257] Fluid Dispersion System for Dispersing a Gas

[0258] Yet another aspect of the present invention is a fluid dispersionsystem for dispersing a gas. The system includes any of the apparatusfor delivery of a gas described herein, and a fluid dispersionapparatus. The fluid dispersion apparatus can disperse liquids and/orgasses. The apparatus for delivery of a gas can be placed at any pointof the fluid dispersion apparatus, e.g., in a liquid reservoir or afluid outlet of the fluid dispersion apparatus, so that gas is generatedand dispersed. The fluid dispersion apparatus can be any fluiddispersion apparatus known in the art, including vaporizers,humidifiers, sonicators that disperse fluid, atomizers, and carpetcleaners.

[0259]FIG. 24 depicts an exemplary embodiment of a fluid dispersionsystem 1800 constructed in accordance with the present invention. Thefluid dispersion system 1800 includes a fluid dispersion apparatus 1810,and a gas delivery apparatus 1820. The gas delivery apparatus 1820includes a sachet 1830 and a reactant 1840 disposed in the volumedefined by the sachet 1830 that generates gas in the presence of aninitiating agent. In this embodiment the fluid dispersion apparatus 1810is a humidifier and the sachet is disposed in a fluid reservoir 1845.The reservoir contains a fluid 1850 that includes an initiating agent.Alternatively, the sachet can be disposed in a dispersion outlet asshown in FIGS. 25 and 26.

[0260] The gas delivery apparatus 1820 can be any of the gas deliveryapparatus described herein. For example, the sachet 1830 can comprisetwo adjacent sachet layers, a barrier layer adjacent a sachet layer, ora rigid frame defining an opening and a sachet layer disposed about theopening. The sachet 1820 can also include further sachets, one or moreenvelope and/or envelope layers, further reactants, and additives, suchas stabilizers and desiccants (not shown). The sachet can be affixedwithin the fluid dispersion apparatus by mechanical means, can floatfreely in the fluid reservoir, or it can include a weight or beconstructed from material such that the sachet sinks to the bottom ofthe reservoir as shown in FIG. 24.

[0261] The fluid dispersion apparatus 1810 includes a means of atomizingthe fluid 1858, and an opening 1854 through which the atomized fluidcontaining the gas exits the fluid dispersion apparatus 1810. Means foratomizing fluids are well known.

[0262] The fluid dispersion 1810 apparatus can be any fluid dispersionapparatus known in the art. The fluid dispersion apparatus can dispersefluid by any means, including mechanical means, sonication, atomization,and/or vaporization. Many such fluid dispersion apparatus suitable foruse with the present invention are readily available commercially aswell as to consumers, for example, DURACRAFT™ Cool Mist™ humidifiersfrom Honeywell Consumer Products (Framingham, Mass.), which draws liquidinto a rapidly spinning wheel with small openings and disperses atomizedfluid into the environment. Also suitable are apparatus that dispersefluid by passing air over a wick that is in contact with a liquid suchas the Cool MoistureTM Humidifier made by Honeywell Consumer Products.

[0263] In another aspect of the present invention, the fluid dispersionsystem can include a housing is provided that contains a gas deliveryapparatus. The housing can be placed or affixed to a fluid dispersionapparatus outlet so that fluid exiting the fluid dispersion apparatuspasses through the gas delivery apparatus so that gas and fluid exit thehousing and enter the environment.

[0264]FIG. 25 depicts a housing for use with a fluid dispersion systemin accordance with the present invention. The housing 1900 can beattached, e.g., to the fluid dispersion apparatus 1810 depicted in FIG.24. The housing 1900 defines an opening 1910 defined by the housing forfluid dispersed by the fluid dispersion apparatus, and openings 1914,for expelling gas and fluid. Disposed in the housing 1900 is a sachet1930 and a reactant 1940 disposed in the volume defined by the sachetthat generates gas in the presence of an initiating agent. The housing1900 can be attached to the fluid outlet of any fluid dispersionapparatus and the sachet 1930 can be used instead of or in addition to asachet in the dispersion apparatus reservoir as depicted in FIG. 24.

[0265]FIG. 26 depicts another exemplary embodiment of a fluid dispersionsystem 2000 constructed in accordance with the present invention. Thefluid dispersion system 2000 includes a fluid dispersion apparatus 2010,a housing 2020, and a gas delivery apparatus 2030. The gas deliveryapparatus 2030 includes a sachet 2034 and a reactant 2038 disposed inthe volume defined by the sachet that generates gas in the presence ofan initiating agent. In this embodiment the fluid dispersion apparatus2000 is a humidifier and the sachet 2034 is disposed in the housing2020. The reservoir contains a fluid 2040 that includes an initiatingagent.

[0266] The fluid dispersion apparatus 2010 includes a means of atomizingthe fluid 2044, and an opening 2048 through which the atomized fluidcontaining the gas exits the fluid dispersion apparatus 2010 and entersthe housing 2020. The housing 2020 defines openings 2050 that allow exitof the gas and the atomized fluid from the housing 2020.

[0267] The gas delivery apparatus 2030 is disposed within the housingand can be attached or affixed to the housing. The sachet includes arigid frame 2054 defining a first opening 2056 and a second opening2058. The sachet further includes a first sachet layer 2060 and a secondsachet layer 2064 disposed about the first opening 2056 and the secondopening 2058, respectively. The sachet can be affixed or removablyattached to the housing by any known means (not shown), e.g., a snapfit.

[0268] Alternatively, the gas delivery apparatus 2030 can be any of thegas delivery embodiments described herein. For example, the gas deliveryapparatus can further include additional sachets, sachet layers,envelope layers, envelopes, additional reactant and/or additives asdescribed herein. The gas dispersion apparatus can be any gas dispersionapparatus including those described above.

[0269] The fluid dispersion system described herein can be used tosanitize, deodorize and/or reduce or eliminate bacteria in a fluidreservoir of the fluid dispersion apparatus, e.g., water in a humidifieror vaporizer. Additionally or alternatively, the system can be used todisperse chlorine dioxide and/or other gases into the environment todestroy or mask odor-causing compounds. The systems also could be usedto disinfect the surrounding environment and kill or inactivatepathogens, such as anthrax, smallpox, tuberculosis, or legionella.

[0270] A preferred method of deodorizing includes the steps of providinga fluid dispersion system as described above, and delivering the gas toone or more odor-causing compounds, wherein the gas inactivates the oneor more odor-causing compounds. A preferred method of inactivatingpathogens includes the steps of providing the fluid dispersion systemdescribed above and delivering the gas to one or more pathogens, whereinthe gas inactivates the one or more pathogens, such as anthrax,smallpox, tuberculosis, or legionella.

[0271] Apparatus for Delivery of a Gas to a Reservoir and/or Conduit

[0272] Yet another aspect of the present invention is a method andapparatus for delivery of a gas to a reservoir. The apparatus generallyincludes any apparatus for delivery of a gas described herein in fluidconnection with a reservoir. One such apparatus is depicted in FIG. 18,wherein the tubular bottle 1106 is the reservoir, and insert 1132,disposed within tubular bottle 1106, is the apparatus for delivery of agas. The gas can further be delivered from the reservoir to a dispersionapparatus such as the pump mechanism 1112, or a humidifier as shown inFIGS. 24 and 26. Another exemplary apparatus is depicted in FIG. 16B,wherein the cap 985 and spout 880 define the reservoir, and the barrierlayer 950 and sachet layer 930 define the sachet. The cap depicted inFIG. 16B can be coupled to a pouch as described or to a conduit (notshown). FIG. 27 depicts another exemplary embodiment of an apparatus2100 for delivery of a gas to a reservoir. The apparatus 2100 generallyincludes a sachet 2110, a reactant 2120 disposed within the volumedefined by the sachet 2110, and a reservoir 2130. The sachet 2110includes a sachet layer 2112, a barrier layer 2114. An envelope layer2118 is disposed adjacent the sachet layer 2112. Disposed in the volumedefined by the sachet 2110 is a second sachet 2140 constructed from twosachet layers 2142, 2144, and a second reactant 2148 disposed in thesecond sachet 2140.

[0273] The reservoir 2130 has first end adapted to couple to a secondreservoir 2150, so that the reservoir 2130 can be detached from thesecond reservoir 2150 for removal and replacement of the sachet 2110,the reactant 2120, the second sachet 2140 and second reactant 2148. Thesecond reservoir 2150 comprises a first end 2152 adapted to couple tothe reservoir 2130, and a second end 2154 adapted to couple to a conduit2160. Conduit 2160 is formed to define an inlet 2162 for fluid to enterreservoir 2130, and an outlet 2164 with tubular member 2168 for fluid toexit reservoir 2130.

[0274]FIG. 28 depicts yet another exemplary embodiment of an apparatus2200 for delivery of a gas to a reservoir. The apparatus 2200 includes areservoir 2240, a first sachet 2210, a first reactant 2214 disposed inthe volume defined by the first sachet 2210, a second sachet 2220, and asecond reactant 2224 disposed in the volume defined by the second sachet2224. The first sachet 2210 and the second sachet 2220 each areconstructed from two adjacent sachet layers sealed about theirperimeters to define a closed receptacle for the first reactant 2214 andthe second reactant 2224, respectively.

[0275] The sachets may be constructed from any of the materialsdescribed herein. The reactants can include any of the reactantsdescribed herein and can further include additives such as flow agents,desiccants and stabilizers. The apparatus can further include additionalenvelopes or sachets (not shown).

[0276] The apparatus further includes a frangible pouch 2230 disposedwithin the reservoir 2240, an initiating agent 2232 disposed within thefrangible pouch 2230, and a sock 2234 disposed about the frangible pouch2230. The sock 2234 can be constructed from any material that does notimpede the passage of initiating agent out of it and that substantiallyretains the frangible pouch 2230 after it is disrupted. The sock 2234 isoptional, but desirable when the frangible pouch is constructed ofbrittle materials, e.g., brittle plastic or glass, so that the frangiblepouch pieces are substantially retained within the sock. Examples ofsock materials suitable for use in accordance with the present inventionare meshes made from polymers or natural fibers such as cotton orcellulose, or non-wovens such as TYVEK® non-woven materials made byDuPont Company (Wilmington, Del.) or the non-woven materials sold byMarubeni Corporation (Tokyo, Japan).

[0277] The apparatus further includes a piston 2250 mounted to thereservoir 2240 that upon actuation disrupts the frangible pouch 2230.Reservoir 2140 includes a first end 2244 adapted to couple to a conduit2260, and a retaining layer 2248 that retains the sachets 2210, 2220 andthe frangible pouch 2230 in the reservoir 2140. Upon disruption of thefrangible pouch 2230, the initiating agent 2232 is released and reactionis initiated. The sock 2234 retains the pieces of the frangible pouch2230.

[0278] Many variations and alternative designs can readily be madewithout departing from the spirit and scope of the invention. Forexample, the sachets can be replaced by any of the gas deliveryapparatus described herein and/or they can be further contained inadditional sachets or envelopes. For example, the sachets, frangiblepouch, and sock can be enclosed within a sachet or envelope attached tothe reservoir and the retaining layer not included such that the outersachet or envelope retains the sachets, frangible pouch and sock in thereservoir. Any of the reactants described herein can be used. Reactantscan be mixed or separated, e.g., by a sachet or an intermediate layer.Additives can also be included in the apparatus, such as activatedhydrotalcite. The conduit can be any conduit, such as a beverage line.

[0279] Yet another aspect of the present invention is a method ofdelivering a gas to a conduit. The method include the steps of providingan apparatus for delivery of a gas including a sachet and a reactantdisposed within the volume defined by the sachet that generates a gas inthe presence of an initiating agent, and a reservoir in fluidcommunication with the sachet. The method further includes the steps ofcoupling the apparatus to a conduit, and delivering a gas to the conduitby introducing an initiating agent to the reactant.

[0280] The conduit can be any conduit where introduction of a gas isdesired. Introduction of a gas, e.g., chlorine dioxide, is particularlyuseful when it is desired to sanitize, disinfect, remove biofilms,and/or kill, inhibit or inactivate pathogens in an aqueous fluid, gas orliquid. The apparatus can be used to flush and clean out conduitsbetween regular usage or to introduce chlorine dioxide gas duringregular usage. The conduit can be a food or beverage conduit, such as abeverage line in a beverage dispensing machine, a conduit in equipmentused to make food or beverages, or a water line in a water dispensersuch as a fountain or bubbler. The conduit can be part of a dentalapparatus such as a water line. The conduit can be part of a medicalapparatus, such as an analyzer. The conduit can be a conduit in acommercial or household appliance such as a dishwasher or coffeemaker.

EXAMPLE 1 An Apparatus in Accordance with the Present Invention

[0281] A membrane sachet was constructed by impulse scaling theperimeter of two 3 cm×3 cm sheets of 0.65 micron pore hydrophilicpolypropylene membrane sold under the trade designation MPLC obtainedfrom Millipore (Bedford, Mass.). The sheets were impulse sealed a 16″TISH400 Impulse Sealer available from TEW Electric Heating EquipmentCorporation (Taiwan). This sachet was filled with 50 mg of sodiumchlorite and 200 mg citric acid. The sachet was then placed into anenvelope formed by impulse sealing the perimeter of a 4 cm×6 cmperforated film. The perforated film used was a SM700 Cryovac®perforated film from Sealed Air Corporation (Duncan, S.C.). Thisassembly was then placed in a 1 liter plastic bag filled with water for15 minutes. The chlorine dioxide concentration in the water was measuredusing a Beckman DU-520 UV-Vis Spectrophotometer set at a wavelength of360 λ at about 6 mg/L.

COMPARATIVE EXAMPLE 2 Direct Addition of Reactant to Water

[0282] 50 mg of sodium chlorite and 200 mg citric acid were added to 1liter of water. The solution was allowed to sit for 15 minutes. Thechlorine dioxide concentration in the water was measured using a BeckmanDU-520 UV-Vis Spectrophotometer set at a wavelength of 360 λ at about0.5 mg/L. FIGS. 8 and 10 depict gas generation over time for adding thesame amount and ratio of reactants to water.

EXAMPLE 3 An Apparatus Without an Envelope

[0283] An apparatus was constructed as described in Example 1, exceptthat the envelope was not included. This assembly was then placed in a 1liter plastic bag filled with water for 15 minutes. The chlorine dioxideconcentration in the water was measured using a Beckman DU-520 UV-VisSpectrophotometer set at a wavelength of 360 λ at about 5.5 mg/L. Suchan apparatus and exemplary use of the same are depicted in FIG. 10.

EXAMPLE 4 An Apparatus Having Two Sachets

[0284] Two sachets were constructed by impulse sealing the perimeter offour 3 cm×3 cm sheets of 0.65 micron pore hydrophilic polypropylenemembrane sold under the trade designation MPLC obtained from Millipore(Bedford, Mass.). The first sachet was filled with 400 mg of sodiumchlorite and the second sachet was filled with 1200 mg citric acid. Bothsachets were then enclosed in an envelope formed by impulse sealing theperimeter of a 4 cm×6 cm SM700 film obtained from Sealed Air Corporationhaving 330 holes per square inch having a diameter of 0.4 mm, a 6.4%perforated area and a water vapor transmission rate of 700 g/m²/24 hr.This apparatus was then placed in a 1 liter plastic bag filled withwater and let stand for 180 minutes. The chlorine dioxide concentrationwas measured using a Beckman DU-520 UV-Vis Spectrophotometer set at awavelength of 360 λ 100 mg/L.

EXAMPLE 5 An Apparatus Having Three Sachets and a Frangible PouchContaining an Initiating Agent

[0285] Two sachets were constructed in accordance with Example 4 exceptthat the sachets were constructed from 3 micron pore nylon 6,6 materialsold under the trade designation BIODYNE A from Pall (Port Washington,N.Y.). The first sachet was filled with 500 mg of sodium chlorite andthe second sachet was filled with 2000 mg citric acid. Both sachets werethen enclosed in a third sachet formed by impulse sealing the perimeterof a 5 cm×7 cm 0.65 micron pore, hydrophobic polypropylene membrane soldunder the trade designation DOHP by Millipore (Bedford, Mass.). Afrangible pouch was constructed and filled with 5 ml of water. Thefrangible pouch and the third sachet (containing the first and secondsachets and reactant) were then enclosed in an envelope formed byimpulse sealing the perimeter of a 7 cm×9 cm multilayered polymer filmhaving a carbon dioxide transmission rate of 7,000 cc/m²/24 hrs and anoxygen transmission rate of 21,000 cc/m²/24 hrs sold under the tradedesignation PD-961 Cryovac® selective transmission film from Sealed AirCorporation (Duncan, S.C.). The frangible pouch was burst using manualpressure and this apparatus was then placed in a 1 liter plastic bagfilled with water and let stand for 180 minutes. The chlorine dioxideconcentration in the water was measured using a Beckman DU-520 UV-VisSpectrophotometer set at 360 λ at 100 mg/L.

EXAMPLE 6 An Apparatus Having an Envelope and a Bridge

[0286] A two-compartment membrane sachet was constructed by impulsesealing the perimeter of a 3 cm×3 cm sheets of 0.65 micron porehydrophilic polypropylene membrane, sold under the trade designationMPLC obtained from Millipore (Bedford, Mass.), between two 3 cm×3 cmsheets of 0.65 micron pore hydrophobic polypropylene membrane sold underthe trade designation DOHP by Millipore (Bedford, Mass.). Thus wasformed a two compartment sachet having hydrophilic membrane on its outerwalls and a divider of hydrophobic membrane for separating the reactantin each compartment. The first compartment of the sachet was filled with50 mg of sodium chlorite and the second compartment was filled with 200mg citric acid. This multi-compartment sachet was then placed into anenvelope formed by heat-sealing the perimeter of a 4 cm×6 cm perforatedfilm. The perforated film used was a SM700 Cryovac® perforated film fromSealed Air Corporation (Duncan, S.C.). This assembly was then placed ina 1 liter plastic bag filled with water for 15 minutes. The chlorinedioxide concentration in the water was measured using a Beckman DU-520UV-Vis Spectrophotometer set at 360 λ wavelength at about 8 mg/L.

EXAMPLE 7 An Apparatus for Generating Carbon Dioxide

[0287] A sachet was constructed by impulse sealing the perimeter of two3 cm×3 cm sheets of 0.65 micron pore hydrophilic polypropylene membrane,sold under the trade designation MPLC obtained from Millipore (Bedford,Mass.). This sachet was filled with 50 mg of calcium carbonate and 100mg citric acid. The sachet was then placed into an envelope formed byimpulse sealing the perimeter of a 4 cm×6 cm perforated film. Theperforated film used was a SM700 Cryovac® perforated film from SealedAir Corporation (Duncan, S.C.). This assembly was then placed in a 1liter plastic bag filled with water for 15 minutes. The carbon dioxideconcentration in the water was measured using analyzed by ionchromatography at about 50 mg/L.

EXAMPLE 8 An Apparatus for Long-Term Release

[0288] A sachet was constructed by impulse sealing the perimeter of two4 cm×6 cm sheets of 0.65 micron pore hydrophilic polypropylene membrane,sold under the trade designation MPLC obtained from Millipore (Bedford,Mass.). This sachet was filled with 500 mg of sodium chlorite and 2000mg citric acid. The sachet was then placed into an envelope formed byimpulse sealing the perimeter of a 4 cm×6 cm perforated film. Theperforated film used was 0.1 micron pore hydrophobic polypropylenemembrane sold under the trade designation DOHP by Millipore (Bedford,Mass.). This apparatus was then placed in a 2 liter plastic bag filledwith water. The chlorine dioxide concentration was measured every hourusing a Beckman DU-520 UV-Vis Spectrophotometer set at a wavelength of360 λ. The apparatus generated about 3.5 mg per hour for 30 hours.

EXAMPLE 9 An Exemplary Apparatus in Accordance with the PresentInvention

[0289] An exemplary apparatus was constructed by sealing the perimeterof 6.1 cm diameter sheets of nylon 6,6 membrane layer sold under thetrade designation 045ZY by Cuno Incorporated (Meriden, Conn.) and SM700Cryovac® perforated film from Sealed Air Corporation (Duncan, S.C.) to abarrier layer filled with 240 mg of sodium chlorite, 60 mg of activatedhydrotalcite, and 1,200 mg citric acid. The barrier layer was formedfrom polyvinyl chloride to define a barrier layer similar to barrierlayer 50 depicted in FIGS. 12A, 12B and 12C. It had an outside adiameter of 6 cm and a 0.5 cm deep cavity formed therein having a 4.8 cminside diameter. The layers were sealed about the edge of the barrierlayer with an epoxy adhesive between the impermeable layer and the nylon6,6 membrane layer, and between the nylon 6,6 membrane layer and theperforated film layer. The surface area of the nylon 6,6 layer adjacentto the reactant was about 18 cm² and the volume defined by the barrierlayer and the nylon 6,6 layer was about 9 cm³. This assembly wasattached by a snap fit to the interior wall of a polypropylene caphaving a threaded fit to the spout of a 1 liter blow molded high densitypolyethylene plastic bottle. The bottle was filled with 1 liter ofwater, sealed with the cap, and turned upside down and left to stand.The chlorine dioxide concentration in the water was measured using aHach DR890 Colorimeter and the standard Hach chlorine dioxide method atabout 25 mg/L at 45 minutes and about 42 mg/L at 60 minutes. HachColorimeters are available from Hach Company (Loveland, Colo.). Asimilar apparatus and exemplary use of the same are depicted in FIGS.16A and 16B.

PROSPECTIVE EXAMPLE 10 An Exemplary Apparatus with a Sachet and Envelope

[0290] A membrane sachet will be constructed by impulse sealing theperimeter of two 3 cm×3 cm sheets of nylon 6,6 membrane layer sold underthe trade designation 045ZY by Cuno Incorporated (Meriden, Conn.). Thesheets are to be impulse sealed with a 16″ TISH400 Impulse Sealeravailable from TEW Electric Heating Equipment Corporation (Taiwan). Thissachet will be filled with 240 mg of sodium chlorite, 60 mg of activatedhydrotalcite, and 1,200 mg citric acid. The sachet will then be placedinto an envelope formed by impulse sealing the perimeter of a 4 cm×6 cmperforated film. The perforated film used will be a SM700 Cryovac®perforated film from Sealed Air Corporation (Duncan, S.C.). Thisassembly will then be placed in a 1 liter plastic bag filled with waterfor 15 minutes. The chlorine dioxide concentration in the water will bemeasured using a Hach DR890 Colorimeter and the standard Hach chlorinedioxide method. It is expected that readings of about 25 mg/L at 45minutes and about 42 mg/L at 60 minutes will be obtained. Such anapparatus and exemplary use of the same are depicted in FIGS. 1A and 1B.

PROSPECTIVE EXAMPLE 11 An Exemplary Apparatus Including a Pouch and aSealed Spout

[0291] An exemplary apparatus will be constructed as described inExample 9, except that this assembly will be fused to the interior wallof a one liter pouch. The pouch will be constructed from a 5 mil thickimpermeable layer comprising a polyester exterior, a metallizedbiaxially oriented core, and a polyethylene interior sealing layerobtained from Sealed Air Corporation (Duncan, S.C.). This layer has awater vapor transmission rate of 0.01 g/100 in2/24 hours at 70% relativehumidity and 122° F. The spout will be constructed of injection moldedpolypropylene. The pouch will be sealed about its perimeter except forthe opening defined by the spout. The one liter pouch will then befilled with water, capped, and allowed to stand. The chlorine dioxideconcentration in the water will be measured as described in Example 9and similar chlorine dioxide concentrations are expected at 45 and 60minutes. Such an apparatus and exemplary use of the same are depicted inFIG. 15.

EXAMPLE 12 Apparatus Having Reactants Mixed with Hydrotalcite

[0292] Hydrotalcite, obtained from Alcoa World Chemicals (Leetsdate,Pa.), was activated by disposing the hydrotalcite on a tray in a layernot more than 1 inch thick, and placing the tray in a furnace at 500° C.for one hour. The hydrotalcite was stored in a closed, airtightcontainer. The hydrotalcite was weighed before and after activation, anddemonstrated an approximately 40% weight loss, believed to beattributable to loss of water and carbon dioxide in the furnace. Dry,flaked technical sodium chlorite (80%) obtained from Vulcan Chemical(Birmingham, Ala.), was ground to a mesh particle size range betweenabout 35 mesh and 70 mesh using a mechanical impact milling system(particle size ranged between about 212 microns and 500 microns). Theactivated hydrotalcite was mixed with the ground sodium chlorite to forma mixture of about 80% sodium chlorite and about 20% activatedhydrotalcite by weight. The sodium chlorate/hydrotalcite mixture wasthen mixed in a dry environment (71° F., 40% relative humidity) withdesiccated granular citric acid having a particle size range betweenabout 25 mesh and about 60 mesh. The citric acid was desiccated byexposing it to dry air (less than 40% relative humidity for a period of24 hours with frequent mixing. The resulting mixture was approximately80% citric acid and 20% sodium chlorite/hydrotalcite mixture by weight.

[0293] Approximately 1.75 grams of this mixture was sealed in a sachet.The sachet and a 1 gram molecular sieve desiccant were sealed in a 1liter plastic bag measuring approximately 7.5 inches by 9 inchesconstructed from a composite of a 1 mil thick metallized biaxiallyoriented polypropylene film and a 5 mils thick linear low densitypolyethylene film. The bag was sealed with a polypropylene spout andcap. The apparatus was stored at room temperature, which ranged fromabout 68° F. to about 80° F., and ambient humidity, which ranged fromabout 50% relative humidity to about 90% relative humidity. Theapparatus was stable at 6 months in that no reaction between the sodiumchlorite and the citric acid was detected at 6 months.

EXAMPLE 13 Apparatus Having Two Sachets and Sodium Chlorite Mixed withHydrotalcite

[0294] The reactants and hydrotalcite described in Example 12 wereobtained. The sodium chlorite was ground, the hydrotalcite activated,and the citric acid desiccated, as described in Example 12. A mixture ofapproximately 95% sodium chlorite and 5% activated hydrotalcite byweight was made. Approximately 4.3 grams of this mixture was sealed in afirst sachet, and approximately 20 grams of desiccated citric acid wassealed in a second sachet. These two sachets were sealed in a 5½ inch by3½ inch envelope constructed from hydrophobic, polypropylene non-wovenmembrane sold under the designation 060P1 by Cuno Incorporated (Meriden,Conn.). The sachets and envelope, and 2 grams of molecular sievesdesiccant were sealed in a 2-liter plastic bag measuring approximately7.5 inches by 14 inches constructed from a composite of a 1 mil thickmetallized biaxially oriented polypropylene film and a 5 mils thicklinear low density polyethylene film. The bag was sealed with apolypropylene spout and cap. The apparatus was stored under the sameconditions as described in Example 12. The apparatus was stable at 6months in that no reaction between the sodium chlorite and the citricacid was detected at 6 months.

EXAMPLE 14 Apparatus Having a Sachet Constructed from Water VaporSelective Material

[0295] Six sets of reactant/hydrotalcite mixtures were each prepared forinclusion in a sachet as follows: 350 grams of a mixture ofapproximately 80% sodium chlorite obtained from Vulcan Chemical(Birmingham, Ala.) and 20% activated hydrotalcite obtained from AlcoaWorld Chemicals (Leetsdale, Pa.), was mixed with 1400 milligrams ofdesiccated citric acid from JT Baker (Phillipsburg, N.J.).

[0296] Four of the reactant/hydrotalcite mixtures were each impulsesealed in a sachet constructed from two 1.75 mils thick, 2.5 inch by 2.5inch hydrophobic polytetrafluoroethylene (PTFE) layers having a 1.5micron average nominal pore size thermally bonded to a 5 mil thick,BHA-TEX® hydrophobic polyethylene (PE) support layer from BHATechnologies (Kansas City, Mo.). The remaining two reactant/hydrotalcitemixtures were each impulse sealed in a sachet constructed from two 2.5inch by 2.5 inch, 0.65 micron pore size, extruded hydrophobicpolypropylene layer sold under the trade designation DOHP by Millipore(Bedford, Mass.).

[0297] Each of the six total sachets were sealed in a 1 liter plasticbag filled with water. The chlorine dioxide concentration in the waterwas measured every 10 minutes using a Hach DR890 Colorimeter and thestandard Hach chlorine dioxide method. FIG. 29 is a graph depictingchlorine dioxide concentration versus time comparing the above sachetmaterials. The square-shaped data points correspond to the averagedvalues for the apparatus constructed with the PTFE/PE sachet layers. Thecircle-shaped data points correspond to averaged values for apparatusconstructed with the PP sachet layers. As can be seen from FIG. 29, theapparatus having the PTFE/PE sachet generated chlorine dioxide morerapidly than the apparatus with the PP sachet. This due, at least inpart, to use of a thinner PTFE water vapor selective material, ascompared to the relatively thicker PP water vapor selective material. Inaddition, the apparatus having the PTFE/PE sachet generated morechlorine dioxide, resulting in a more highly concentrated solution thanthe solution generated by the apparatus with the PP membrane.

EXAMPLE 15 Apparatus Having a Rigid Frame

[0298] A rigid frame of PVC pipe, cylindrical in shape and measuringabout 2.54 cm in length, having an inner diameter of about 3.81 cm, andan inner volume of about 29 cm³ was obtained. The first end was sealedwith the PTFE/PE layer used in the preceding example. A mixture ofapproximately 95% sodium chlorite and 5% activated hydrotalcite byweight was made as described in Example 13. About 2.9 grams of themixture was enclosed in a sachet measuring 1.5 inches square, and madeof heat sealable water soluble paper made by Mishima Paper Co. (Tokyo,Japan). The sachet and about 13.6 grams of desiccated citric acid weredisposed in the vessel formed from the rigid frame and the PTFE/PEsachet layer, and a second layer of the same PTFE/PE sachet material wassealed on the second end of the rigid frame, thus forming asubstantially closed sachet volume of about 29 cm³. The layers weresealed to the rigid frame by using Scotch® 300LSE Hi Strength adhesivemade by the 3M Company (Minneapolis, Minn.). The membrane/adhesive/rigidframe bond was allowed to cure for 24 hours prior to use. The resultingapparatus was placed in about 2 liters of water. After 24 hours, thechlorine dioxide concentration was measured using a Hach DR890Colorimeter and the standard Hach chlorine dioxide method. The chlorinedioxide concentration was about 346.7 ppm.

EXAMPLE 16 Apparatus Having an Envelope Constructed with a Water VaporSelective Material

[0299] Seventy sets of reactant envelopes, each containing two reactantsachets, were prepared in the following manner. 4.3 grams of a mixtureof approximately 95% technical grade sodium chlorite obtained fromVulcan Chemicals (Birmingham, Ala.), and 5% activated hydrotalciteobtained from Alcoa World Chemicals (Leetsdale, Pa.), were sealed in a2.75 inch×2.75 inch sachet made of heat sealable water soluble papermade by Mishima Paper Co. (Tokyo, Japan). 20 grams of desiccated citricacid monohydrate obtained from J. T. Baker (Phillipsburg, N.J.), weresealed inside a second sachet, measuring 3.25 inches×4 inches, also madeof rice paper. These two sachets were then sealed inside a hydrophobicenvelope having dimensions of 4.75 inches×4 inches.

[0300] Sixty-seven sets of reactant sachets impulse sealed in a watervapor selective envelope constructed of a non-woven polypropylenemembrane sold under the trade designation S8500240H by Cuno Incorporated(Meridan, Conn.). The remaining three sets of reactant sachets werescaled, using Scotch™ 300LSE Hi Strength Adhesive (3M Corporation,Minneapolis, Minn.), in a water vapor selective envelope constructed ofa 1.75 mil thick PTFE layers thermally bonded to a 5 mil thickpolyethylene (PE) mesh support material resulting in a final envelopematerial thickness of approximately 5 mils which is sold under the tradedesignation BHA-TEX® by BHA Technologies (Kansas City, Mo.). Theenvelopes were constructed with the PTFE layer on the inside, near thereactant sachets, and the adhesive was allowed to cure for 24 hoursprior to testing.

[0301] Each of the seventy envelopes was sealed in a 2-liter plastic bagthat was filled with liquid water. The chlorine dioxide concentration inthe water was measured periodically, over a 24-hour period, using a HachDR890 Colorimeter and the standard Hach chlorine dioxide method. FIG. 30is a graph depicting the chlorine dioxide concentration versus timecomparing the above envelope materials. The diamond-shaped data pointscorrespond to the averaged values for the apparatus constructed with thenon-woven polypropylene envelope material. The square-shaped data pointscorrespond to the averaged values for the apparatus constructed with thePTFE/PE composite envelope material. As can be seen from FIG. 30, theapparatus having the PTFE/PE envelope generated chlorine dioxide morerapidly than the apparatus with the polypropylene envelope.

[0302] Although generally the preferred embodiments of the inventionhave been shown and described, numerous variations and alternativeembodiments will occur to those skilled in the art. Accordingly, it isintended that the invention be limited only in terms of the appendedclaims as the invention can be embodied in other specific forms.

What is claimed is:
 1. An apparatus for delivery of a gas comprising: asachet comprising a water vapor selective material; and a reactantdisposed within the sachet that generates a gas in the presence of aninitiating agent.
 2. The apparatus of claim 1, wherein the water vaporselective material has a thickness between about 0.15 mils and 15 mils,and a nominal average pore size between about 0.05 microns and about 10microns.
 3. The apparatus of claim 1, wherein the sachet furthercomprises a support layer disposed adjacent the water vapor selectivematerial.
 4. The apparatus of claim 1, wherein the water vapor selectivematerial has a water vapor transmission rate between about 2,000 g/m²/24hrs and about 150,000 g/m²/24 hrs.
 5. The apparatus of claim 1, whereinthe reactant is selected from the group consisting of acids, aqueousacids, citric acid, oxalic acid, fumaric acid, phosphoric acid,potassium bitartate, chlorites, chlorates, sulfites, bisulfites,sulfates, carbonate, nitrites, and combinations thereof.
 6. Theapparatus of claim 1, further comprising: a second sachet disposed inthe sachet; and a second reactant disposed in the second sachet.
 7. Anapparatus for delivery of a gas comprising: a sachet comprising a watervapor selective material; a partition disposed within the sachetdefining a first volume and a second volume; a first reactant disposedin the first volume; and a second reactant disposed within the secondvolume, wherein the first reactant and the second reactant generate agas in the presence of an initiating agent.
 8. An apparatus for deliveryof a gas comprising: a barrier layer; a sachet layer comprising watervapor selective material disposed adjacent to the barrier layer; and areactant disposed in a volume defined by the barrier layer and thesachet layer that generates a gas in the presence of an initiatingagent.
 9. The apparatus of claim 8, wherein the water vapor selectivematerial has a thickness between about 0.15 mils and 15 mils, and anominal average pore size between about 0.05 microns and about 10microns.
 10. The apparatus of claim 8, wherein the sachet layer furthercomprises a support layer disposed adjacent the water vapor selectivematerial.
 11. The apparatus of claim 8, wherein the water vaporselective material has a water vapor transmission rate between about2,000 g/m²/24 hrs and about 150,000 g/m²/24 hrs.
 12. The apparatus ofclaim 8, further comprising an envelope layer disposed adjacent thesachet layer.
 13. The apparatus of claim 8, further comprising anintermediate layer disposed between the sachet layer and the barrierlayer such that the reactant is disposed in a volume defined by thebarrier layer and the intermediate layer.
 14. The apparatus of claim 12,further comprising a second reactant disposed in a volume defined by theintermediate layer and the sachet layer.
 15. An apparatus for deliveryof a gas comprising: a sachet comprising a rigid frame defining anopening and a sachet layer disposed about the opening; and a reactantdisposed in the sachet, wherein the reactant generates a gas in thepresence of an initiating agent.
 16. The apparatus of claim 15, furthercomprising: a second opening defined by the rigid frame; and a secondsachet layer disposed about the second opening.
 17. The apparatus ofclaim 15, wherein the rigid frame is tubular and has a circularcross-section.
 18. The apparatus of claim 15, wherein the reactant isselected from the group consisting of acids, aqueous acids, citric acid,oxalic acid, fumaric acid, phosphoric acid, potassium bitartate,chlorites, chlorates, sulfites, bisulfites, sulfates, carbonate,nitrites, and combinations thereof.
 19. The apparatus of claim 15,comprising: a second sachet disposed in the sachet; and a secondreactant disposed in the second sachet.
 20. The apparatus of claim 15,wherein the sachet layer comprises a water vapor selective material. 21.The apparatus of claim 15, comprising an envelope layer disposedadjacent the sachet layer.
 22. The apparatus of claim 15, comprising apartition layer disposed within the sachet defining a first volume and asecond volume.
 23. The apparatus of claim 22, wherein the reactant isdisposed in the first volume, and further comprising a second reactantdisposed in the second volume.
 24. The apparatus of claim 16, whereinthe sachet layer comprises a water vapor selective material, and thesecond sachet layer comprises a material that restricts or prevents thetransmission of liquid water and water vapor after hydration.
 25. Afluid dispersion system for dispersing a gas comprising: a fluiddispersion apparatus; and an apparatus for delivery of a gas disposedwithin the fluid dispersion apparatus, the apparatus comprising: asachet, and a reactant disposed in the sachet that generates gas in thepresence of an initiating agent.
 26. The system of claim 25, wherein thefluid dispersion apparatus is a humidifier, and the apparatus fordelivery of a gas is disposed in a fluid reservoir defined by the fluiddispersion apparatus.
 27. The system of claim 25, wherein the fluiddispersion apparatus is a humidifier, and the apparatus for delivery ofa gas is disposed in a dispersion outlet defined by the fluid dispersionapparatus.
 28. The system of claim 25, wherein the sachet comprises abarrier layer and a sachet layer disposed adjacent to the barrier layer.29. The system of claim 25, wherein the sachet comprises a rigid framedefining an opening and a sachet layer disposed about the opening. 30.The system of claim 25, wherein the reactant is selected from the groupconsisting of acids, aqueous acids, citric acid, oxalic acid, fumaricacid, phosphoric acid, potassium bitartate, chlorites, chlorates,sulfites, bisulfites, sulfates, carbonate, nitrites, and combinationsthereof.
 31. A method of deodorizing comprising the steps of: providingthe fluid dispersion system of claim 25; and delivering the gas to oneor more odor-causing compounds, wherein the gas inactivates the one ormore odor-causing compounds.
 32. A method of inactivating pathogenscomprising the steps of: providing the fluid dispersion system of claim25; and delivering the gas to one or more pathogens, wherein the gasinactivates the one or more pathogens.
 33. An apparatus for delivery ofa gas to a reservoir comprising: a sachet; a reactant disposed withinthe sachet; and a reservoir in fluid communication with the sachet,wherein the reactant generates a gas in the presence of an initiatingagent.
 34. The apparatus of claim 33, wherein the sachet comprises abarrier layer disposed adjacent a sachet layer.
 35. The apparatus ofclaim 33, wherein the sachet comprises a first sachet layer disposedadjacent a second sachet layer.
 36. The apparatus of claim 33, whereinthe sachet comprises a rigid frame defining an opening and a sachetlayer disposed about the opening.
 37. The apparatus of claim 33,comprising wherein the reactant is selected from the group consisting ofacids, aqueous acids, citric acid, oxalic acid, fumaric acid, phosphoricacid, potassium bitartate, chlorites, chlorates, sulfites, bisulfites,sulfates, carbonate, nitrites, and combinations thereof.
 38. Theapparatus of claim 33, wherein the reservoir is a bottle.
 39. Theapparatus of claim 33, wherein the reservoir comprises a first endadapted to couple to a conduit.
 40. The apparatus of claim 33,comprising a second sachet disposed within the sachet, and a secondreactant disposed within the second sachet.
 41. The apparatus of claim33, further comprising a frangible pouch disposed within the reservoir;an initiating agent disposed within the frangible pouch; and a pistonmounted to the cartridge, wherein actuation of the piston disrupts thefrangible pouch releasing the initiating agent.
 42. The apparatus ofclaim 41, wherein the frangible pouch is constructed of glass, and theapparatus further comprises a sock disposed about the frangible pouch.43. The apparatus of claim 33, wherein the reservoir comprises a firstend adapted to couple to a second reservoir, such that the reservoir canbe detached from the second reservoir for removal and replacement of thesachet and the reactant.
 44. A method of delivering gas to a conduitcomprising the steps of: providing an apparatus for delivery of a gascomprising: a sachet; a reactant disposed within the sachet thatgenerates a gas in the presence of an initiating agent; and a reservoirin fluid communication with the sachet, coupling the apparatus to aconduit, and delivering a gas to the conduit by introducing aninitiating agent to the reactant.
 45. The method of claim 44, whereinthe conduit is a food or beverage conduit.
 46. The method of claim 44,wherein the conduit is a conduit in a dental apparatus.
 47. The methodof claim 44, wherein the conduit is a conduit in a medical apparatus.48. The method of claim 44, wherein the conduit is a conduit in a wateror beverage dispenser.
 49. The method of claim 44, wherein the conduitis in a humidifier or vaporizer.